• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Model and data of optically controlled tunable capacitor in silicon single-photon avalanche diode

    2023-09-05 08:48:38MeiLingZeng曾美玲YangWang汪洋XiangLiangJin金湘亮YanPeng彭艷andJunLuo羅均
    Chinese Physics B 2023年7期
    關(guān)鍵詞:汪洋美玲

    Mei-Ling Zeng(曾美玲), Yang Wang(汪洋), Xiang-Liang Jin(金湘亮),?, Yan Peng(彭艷), and Jun Luo(羅均)

    1School of Physics and Electronics,Hunan Normal University,Changsha 410081,China

    2School of Mechatronic Engineering and Automation,Shanghai University,Shanghai 200444,China

    Keywords: photocapacitance effect,single-photon avalanche diode,interfacial traps

    1.Introduction

    As a core device in the field of extremely weak light detection, single-photon avalanche diodes (SPADs) fabricated based on the complementary metal–oxide–semiconductor(CMOS) process have been proven to have the advantages of high signal-to-noise ratio, high temporal resolution, and high dynamic range.[1–5]With the continuous development and optimization of image sensing technology, it is possible to manufacture millions of pixels with single-photon detection capability on a single chip.[6]To date, a great deal of research has been conducted to develop SPAD devices with high performance; for example, back-illuminated three-bit stacked SPADs with extremely low tunnel noise and high photon detection probability,[7]SPAD devices with improved photon detection probability by designing antireflection nanostructures,[8]near-infrared enhanced singlephoton detectors,[9,10]et al.With the development of semiconductor technology, semiconductor devices face increasing stability and reliability problems, among which capacitance is an important factor affecting the response speed of the device.However,there are few studies on the capacitance characteristics of SPADs at present, and the research directions mainly focus on broadening the spectral response range, improving the photon detection probability, and optimizing the dark count.[11–19]As a diode, an SPAD exhibits capacitive characteristics in addition to resistive effects when an AC voltage is applied.When forward and reverse voltages are applied across the diode,the diffusion capacitance and barrier capacitance exist respectively.Ideally,both capacitances are derived from the free carrier motion of the device itself.However, in the actual silicon planar process, there are charge traps at the interface between silicon and silicon dioxide.These traps are likely to exchange charges with free carriers,which affect the density of carriers in the surface layer of the device, thereby causing capacitance influence.Does this indicate some kind of correlation between the interfacial traps of the semiconductor and the capacitance? A long time ago,the literature[20]reported that the existence of traps in the semiconductor bandgap caused the photocapacitance effect.In the literature,the photocapacitance measurement of GaP materials was used to determine the energy level and concentration of deep traps in the material.In 1997,Tanet al.studied the interface properties of SiO2/SiC through the capacitance–voltage(C–V)method and proposed a formula for calculating the average density of interface defect states.[21]Maet al.analyzed the optical power dependence of capacitance by establishing a differential capacitance model for a single-row carrier photodetector,to optimize the high-speed performance of the detector at different optical powers.[22]Sengougaet al.studied theC–Vcharacteristics of two P-type silicon-doped GaAs Schottky diodes and observed that the deviation of theC–Vcharacteristics was related to the deep body defects with non-uniform density.[23]Reference[24]reported the photocapacitance effect in organic heterojunction devices constituting a PN junction, attributing the photocapacitance effect to charge traps.It can be seen that in semiconductor devices,the capacitance is closely related to the deep trap center of the photocapacitance effect in particular.

    In this work, the capacitive properties of SPADs fabricated in a silicon-based process are investigated,and the photocapacitance effect is also reported.Through a small-signalC–Vtest at room temperature and low frequencies,the capacitance of SPAD devices under light is significantly higher than under no light.As the frequency increases,the gap gradually narrows.We believe this difference in capacitance is related to interfacial traps in the samples.

    2.Device structure and capacitance analysis

    Silicon is easily oxidized to form high-quality silicon dioxide,which allows silicon dioxide to be used as a diffusion mask during device fabrication and as an insulating material for many devices.Figure 1 is a cross-sectional view of the circular single-photon avalanche diode structure designed in this paper, and figure 2 shows the layout of the device (left)and the microscope image of the device based on the 0.18μm standard bipolar-CMOS-DMOS(BCD)process(right).In the fabrication of SPAD devices based on standard silicon technology, a layer of 0.01 μm–0.1 μm silicon dioxide is first thermally grown on a flat P-type silicon wafer as a diffusion mask layer.Next,photolithography is performed on the oxide layer,and the shallow trench isolation(STI)regions are etched and deposited with silicon dioxide.According to the specific structure of the device,multiple photolithography and implantation of high-energy phosphorus ions and boron ions are performed to form a photosensitive PN junction with a diameter of 20μm.After this,an aluminum electrode is formed on the surface of the silicon wafer by reactive sputtering to connect the device to the outside.This work adopts the dual diode structure of a P+/N-well and deep N-well/P substrate.Among them, the P+/N-well can form a high field multiplication region as a photosensitive junction.The deep N-well/P substrate acts as an isolation diode,preventing the photo-generated carriers of the substrate from entering the photosensitive junction and causing charge crosstalk.A P-well guard ring at the edge of the PN junction prevents premature edge breakdown of the device.

    Fig.1.Single-photon avalanche diode(SPAD)structure.

    Fig.2.Layout and microscope images of SPAD devices.

    SPADs need to work in a reverse-biased state, i.e., the cathode is connected to a high potential, and the anode is grounded.The two-dimensional simulation of the device is carried out in a technology computer-aided design (TCAD)simulator to obtain the electric field distribution at each position of the device in Geiger mode,as shown in Fig.3.Due to the different doping concentrations,the widths of the depletion regions of the P+/N-well,P-well/N-well,and P-well/deep Nwell junctions are different.When the device is reverse biased,the PN junction is equivalent to a large resistance and the voltage drop mainly exists in the depletion region,so the width of the depletion region can be observed through the electric field distribution.The simulation results show that the electric field strength of the central P+/N-well junction is the largest,so the avalanche breakdown is concentrated in the central P+/N-well junction and the device works normally.According to Shockley’s theory,the diode barrier capacitance can be expressed as

    whereεrandε0are the relative permittivity of silicon (11.9)and the vacuum permittivity (8.854×10?12F/m),Ais the cross-sectional area of the junction, andWis the width of the depletion region of the PN junction.The electric field affects the widthWof the depletion region, and the equivalent capacitance distribution in the SPAD device in Fig.4 can be obtained from the electric field distribution.C1is the capacitance of the photosensitive PN junction.C2,C3are the side junction capacitances of the guard ring/N-well,andC4is the guard ring/deep N-well junction capacitance.The parasitic capacitance between the deep N-well and the substrate is independent of the capacitance between the cathode and anode, so it is not indicated in the figure.The total capacitance when the SPAD device is reverse biased can be expressed asCSPAD=C1+C2+C3+C4.Equation (1) introduces the relationship between the capacitance and the width of the depletion region.During the electrostatic analysis of the abrupt junction,it is found that the dependence ofWand the bias voltage varies with the impurity distribution.The specific formula is

    whereqis the electronic charge (1.6×10?19C),NBis the impurity concentration on the lightly doped side,Vbiis the junction potential, andVRis the applied reverse bias voltage.Equation(2)can be substituted into Eq.(1)to get

    It can be seen from Eq.(3) that the barrier capacitance is related to the junction area and impurity concentration.

    Fig.3.Electric field distribution of the SPAD device operating in Geiger mode.

    Fig.4.Equivalent capacitance distribution of the SPAD device.

    However, for silicon-based photodetectors, illumination can affect the carrier concentration inside the device.It can be expressed as the following process: when a photon with energy exceeding the silicon bandgap(1.12 eV)irradiates the device,it can excite an electron from the valence band to the conduction band and leave a hole in the valence band.Electron–hole pairs move directionally in an electric field to form an electric current.Thus illumination increases the free carrier concentration inside the SPAD.The specific concentration of photo-generated carriers per unit time can be expressed asNLight=?I/(qv),where ?Iis the difference between the current and the dark current of the device under illumination,andvis the semiconductor volume.Figure 5 shows the current–voltage (I–V) characteristic curves of the SPAD device designed in this paper tested in light and dark environments(data from the previous work on this subject;see Ref.[25]).As can be seen from the figure,when the SPAD works in linear mode,the photocurrent is several tens of nanoamps higher than the dark current.Therefore, we should modify the capacitance formula to account for the effects of light and dark conditions on the device.We define Eq.(3) as the barrier capacitance under a no-light environment and Eq.(4)as the barrier capacitance under illumination,

    Fig.5.The I–V characteristic curves of the SPAD in light and no-light environments.

    3.Test and discussion

    With a SPAD in reverse bias,when the AC signalvis superimposed on the DC bias, the total voltage drop across the junction isVbias+v.Whenvis at a positive voltage, the AC signal slightly reduces the reverse bias on the junction,i.e.,the charge on both sides of the depletion region is reduced.Whenvchanges in reverse, the total reverse bias voltage across the junction increases immediately,causing an increase in charge on both sides of the junction.The effect of the AC signal can be seen as a small fluctuation of the charge density around its steady-state value.Due to the small magnitude ofv, the displacement of the fluctuating charge at the depletion layer boundary is almost negligible.The alternating increase and decrease of positive and negative charges at the edge of the SPAD depletion region are similar to the principle of physical plate capacitors, and the experiments in this paper are based on this principle to measure the capacitance characteristics of SPAD devices.The test instrument adopts the B1505A system of a power device analysis instrument,which has a touchable liquid crystal display screen for setting parameters, data display,and data processing.The test process is to put the device into the probe box, with the metal probes in contact with the cathode and anode of the SPAD,and superimpose a small sinusoidal signal with an amplitude of 100 mV and adjustable frequency on the DC reverse bias voltage of the device.To measure the photocapacitive effect, the device capacitance is measured in two cases.First,the test box is closed and a dark environment is maintained to measure the dark capacitance of the device.Second,the device’s photocapacitance is measured given a single light source.

    Silicon-based SPAD devices can only respond to visible light,so this test uses red,orange,green,and blue light as light sources and the measured capacitance is represented byCred,Corange,Cgreen, andCblue, respectively, with the dark capacitance represented byCdark.The bias voltage of the device is from 0 V to 5 V,and theC–Vtest results are shown in Fig.6.

    Fig.6.The C–V curves of the device with and without light at 1 kHz frequency.

    As can be seen from the figure, the dark capacitance of the device is around 1.8 pF and the photocapacitance generally fluctuates around 6.3 pF.Moreover,the wavelength of the light source has little effect on the capacitance of the device,which can be ignored.?C=Clight?Cdark≈4.5 pF,indicating that light can increase the junction capacitance of the device,because light excites photo-generated electron–hole pairs and increases the carrier concentration.The width of the depletion layer of the PN junction swings around the stable value with a small AC signal,which enables the carriers to respond in time to the AC signal.In silicon-based semiconductor devices,the response time of the majority carrier is in the range of 10?10s or less,indicating that the device can respond to very high signal frequencies.Therefore,we extended our research scope to study the frequency dependence of the capacitance of SPAD devices.

    Figure 7 shows the capacitance variation curves of SPAD devices at frequencies from 1 kHz to 5 MHz.Among them,the blue curves represent capacitance versus voltage measured under a single blue light source at different frequencies.The black curves represent capacitance versus voltage measured in dark conditions at various frequencies,and the additionally marked small graphs show details of the dark capacitance.The figure shows that under the same bias voltage,the dark capacitance of the device remains almost unchanged with increasing frequency.However, with increasing frequency, the photocapacitance decreases significantly.We obtain the preliminary conclusion that the photocapacitance of SPAD increases at low frequencies and decreases at high frequencies.According to Eq.(4), the difference between the dark capacitance and the photocapacitance is caused by the change in the carrier concentration, and the changing trend of the capacitance should be consistent at different frequencies.However,there are differences in the actual test results.

    Fig.7.The C–V curves of dark capacitance and photocapacitance at different frequencies.

    In Ref.[23], the authors observed the frequency dependence of capacitance in different types of deep-level traps,which was also observed in organic heterojunction devices in Ref.[24].The silicon-based SPAD devices fabricated by the planar process all contained the Si–SiO2system,and it is obvious that the movement space of the carriers was mainly in the surface layer of the silicon wafer.With the development of the manufacturing process,the quality and performance of the device have been greatly improved.However,additional charges and traps are still introduced in the Si–SiO2structure.Since the charge distribution is closely linked to the occurrence of vacancies,traps play an important role in the electron transport properties.For example,an SPAD with STI as the guard ring introduces huge noise to the device,[26]because there are many trap states in the STI region filled with SiO2, which trap and release the carriers in the device and increase the after-pulse.Therefore, we attribute this effect of SPAD photocapacitance to the interfacial traps of the Si–SiO2system, which can explain the photocapacitance versus frequency in Fig.7.When the device receives photons with energy greater than the band gap, electrons in the valence band absorb the energy of the photons and are excited into the conduction band to become free electrons.The concentration of photocarriers in light is far greater than that under dark conditions, and the photocapacitance is greater than the dark capacitance.

    Next,the effect of interface traps on photocapacitance is considered.First of all,the interface trap is mainly due to the formation of a“dangling bond”between Si and SiO2(that is,the silicon atom has an atomic bond in a dangling state), or the oxygen atom at the interface is not connected to the silicon atom,but is in an interstitial position or missing.Interface traps introduce energy levels in the forbidden band of the Si–SiO2interface(which generally can be distributed in the whole forbidden band range),and these traps can trap both electrons and holes.If the energy level is electrically neutral when occupied by electrons and positively charged after releasing electrons, it is called a donor interface state; if the energy level is negatively charged after accepting electrons, it is called an acceptor interface state.In semiconductor silicon, the typical response time of the majority carrier is 10?10s or less,so when making capacitance measurements,the majority of the carrier can flow in and out quickly, so the carrier can respond to the AC signal promptly.However, the time constant of the interface state is large and decreases exponentially as the value ofEF?Eiincreases.Therefore, interface traps cannot respond to high-frequency signals.Assuming that the interface state is a donor state, when the device receives a photon, the energy of the electron in the trap absorbs the photon transitions from the forbidden band to the conduction band, thereby affecting the charge distribution inside the device.These trap states are charged and discharged as the bias voltage changes.In the frequency range below 1 MHz,the charge and discharge of the interface traps can follow the low-frequency signal, so the medium photocapacitor includes the trap capacitance,and the change of the total photocapacitance follows the law;that is,it decreases with increasing frequency.After the frequency continues to increase, the interface traps do not respond and do not charge and discharge, so the capacitance at frequencies above 1 MHz is significantly reduced.Since there are no trap states involved, there is only a small change in capacitance from 1 MHz to 5 MHz.The interface state density is an important criterion to measure the quality of the Si–SiO2interface.The interface state density represents the interface defect density per unit area and unit energy(number of defects×cm?2·eV?1):

    In the formula,Qitis the charge amount of the defect state,andEtis the depth of the defect energy level.These trap states act as recombination centers and affect the density and motion of charge carriers within the silicon surface.The interface trap energy is in the silicon forbidden band, and the distribution presents a non-uniform distribution of dense band edges and sparse center bands.Figure 8(a)is a schematic diagram of the energy bands of the SiO2/Si structure containing interfacial traps.Figure 8(b)is an equivalent circuit diagram considering interface traps.

    Fig.8.(a)Schematic of the SiO2/Si band with interface traps,(b)equivalent circuit model considering interface traps.

    HereRAis the total resistance of the SPAD,VBis the breakdown voltage,and the switchSAsimulates the arrival of photons.In the dark state of the SPAD, the internal capacitance of the device is a capacitorCdarkthat does not change with frequency;when the device is in a light environment,the switchSAis closed, and an additional frequency-dependent capacitorClight(ω) is added to the equivalent circuit.When the energy level of the surface trap is displaced relative to the Fermi levelEF, the electron filling state in the trap changes,resulting in a change in charge.The intuitive effect of this change is a change in capacitance.When a reverse bias is applied to the SPAD in Fig.1,the energy band at the P+surface of the central photosensitive region is bent downward,and the energy level of the interface state moves downward relative toEF.When the acceptor state close to the conduction band moves toEF, due to the electrons occupying the acceptor interface state and the electrons accumulating at the surface of Si–SiO2,forming an accumulation phenomenon,there are additional negative charges in the interface state.

    It can be seen that the change in the applied bias voltage causes a charge change in the interface state; that is, the charge–discharge effect occurs in the interface state.The interface defect state can be characterized in theC–Vcurve when the charge of the interface defect is exchanged with the photosensitive region P+, that is, the interface defect captures and emits electrons.Under no-light conditions, the interface defect states below the intermediate energy level of the forbidden band do not have the energy provided by photons and cannot capture and emit electrons normally.When the device absorbs the energy of the photon,the photo-generated carriers are exchanged with the interface defect state,which changes the capture rate of the trap,that is,reduces the lifetime of the trap.In other words,the energy brought by the light affects the emission and capture rates of electrons in the defect, resulting in a shortened trap lifetime.In addition, when the frequency of the small signal applied by the SPAD is high, the filling and release rates of trap states cannot keep up with the AC signal,which leads to a significant decrease in the photocapacitance of the device at high frequencies, and the photocapacitance exhibits frequency dependence.

    4.Conclusion

    The photocapacitance effect of SPADs is experimentally studied.First, to distinguish the general capacitance of the PN junction, SPAD capacitance is divided into dark capacitance and photocapacitance.The photon energy excites the device to generate photogenerated electron–hole pairs, which increases the internal carrier concentration, thereby increasing the capacitance.Second, it is noted that the photocapacitance has a frequency scattering effect, and the capacitance decreases significantly with increasing frequency.This is due to the existence of interface traps in planar silicon devices,and the photon energy affects the trapping rate of interface traps in SPAD devices,resulting in changes in trap lifetime.

    Acknowledgments

    Project supported by the National Natural Science Foundation of China (Grant Nos.62174052 and 61827812), Hunan Science and Technology Department Huxiang High-level Talent Gathering Project (Grant No.2019RS1037), Innovation Project of Science and Technology Department of Hunan Province (Grant No.2020GK2018), and Postgraduate Scientific Research Innovation Project of Hunan Province (Grant No.QL20210131).

    猜你喜歡
    汪洋美玲
    長(zhǎng)大以后做什么
    Polysaccharides Based Random and Unidirectional Aerogels for Thermal and Mechanical Stability
    汪洋作品
    美玲:我的幸福是與萌貨親密接觸
    金色年華(2017年10期)2017-06-21 09:46:49
    趙美玲
    春天的早晨
    渡過語(yǔ)言的汪洋
    亙貫古今的汪洋臺(tái)
    汪洋之中一條船
    精品国产乱码久久久久久小说| 国产精品人妻久久久影院| 国产成人免费观看mmmm| 中文字幕最新亚洲高清| 卡戴珊不雅视频在线播放| 一二三四中文在线观看免费高清| 啦啦啦视频在线资源免费观看| 少妇猛男粗大的猛烈进出视频| 色播在线永久视频| videossex国产| 亚洲国产色片| 丝瓜视频免费看黄片| 制服人妻中文乱码| 精品卡一卡二卡四卡免费| av电影中文网址| 我的亚洲天堂| 久久久久精品性色| 新久久久久国产一级毛片| 欧美97在线视频| 新久久久久国产一级毛片| 免费看不卡的av| 一区福利在线观看| 90打野战视频偷拍视频| 亚洲av欧美aⅴ国产| 国产精品偷伦视频观看了| 少妇人妻久久综合中文| 久久ye,这里只有精品| 大片免费播放器 马上看| 国产精品免费视频内射| av在线app专区| 亚洲精品一二三| 精品国产一区二区三区久久久樱花| 1024视频免费在线观看| 久久久久视频综合| 久久韩国三级中文字幕| 成人二区视频| 蜜桃在线观看..| 国产av精品麻豆| 最新的欧美精品一区二区| 菩萨蛮人人尽说江南好唐韦庄| 免费av中文字幕在线| 国产免费视频播放在线视频| 一边摸一边做爽爽视频免费| 在线观看一区二区三区激情| 国产探花极品一区二区| 91午夜精品亚洲一区二区三区| 99热国产这里只有精品6| 国产精品三级大全| 一级毛片我不卡| 欧美精品亚洲一区二区| 男女午夜视频在线观看| 国产精品二区激情视频| 免费在线观看完整版高清| 90打野战视频偷拍视频| 天天躁夜夜躁狠狠久久av| 中文欧美无线码| 久久久久国产一级毛片高清牌| 在线观看美女被高潮喷水网站| 99久国产av精品国产电影| 青春草国产在线视频| 欧美精品高潮呻吟av久久| 精品少妇黑人巨大在线播放| 汤姆久久久久久久影院中文字幕| 午夜激情久久久久久久| 中文字幕精品免费在线观看视频| 乱人伦中国视频| 亚洲国产精品999| 亚洲欧美一区二区三区黑人 | 亚洲欧洲精品一区二区精品久久久 | 久久久久精品人妻al黑| 免费高清在线观看视频在线观看| 多毛熟女@视频| 精品少妇内射三级| 国产一级毛片在线| 日韩在线高清观看一区二区三区| 国产精品av久久久久免费| 亚洲天堂av无毛| 色视频在线一区二区三区| 成人二区视频| 夫妻性生交免费视频一级片| 久久久久国产一级毛片高清牌| 欧美国产精品va在线观看不卡| 亚洲图色成人| 国产探花极品一区二区| 久久免费观看电影| 久久免费观看电影| 亚洲图色成人| 人妻 亚洲 视频| 天天影视国产精品| 一本一本久久a久久精品综合妖精 国产伦在线观看视频一区 | 丝袜喷水一区| 秋霞伦理黄片| 欧美精品高潮呻吟av久久| 亚洲国产毛片av蜜桃av| 国产在线一区二区三区精| 亚洲国产欧美网| 国产成人精品久久久久久| 亚洲av日韩在线播放| 99精国产麻豆久久婷婷| av有码第一页| 国产精品二区激情视频| 国产精品不卡视频一区二区| 亚洲久久久国产精品| 国产精品二区激情视频| www.av在线官网国产| 你懂的网址亚洲精品在线观看| 成人毛片a级毛片在线播放| 最新的欧美精品一区二区| 日本av免费视频播放| 婷婷色综合大香蕉| 日韩精品有码人妻一区| 久久精品亚洲av国产电影网| 亚洲av欧美aⅴ国产| 只有这里有精品99| 一级毛片黄色毛片免费观看视频| 交换朋友夫妻互换小说| 亚洲成国产人片在线观看| 日日爽夜夜爽网站| 香蕉精品网在线| 免费看不卡的av| 久久久欧美国产精品| 日本-黄色视频高清免费观看| 哪个播放器可以免费观看大片| 97在线视频观看| 高清欧美精品videossex| 男人舔女人的私密视频| 亚洲国产日韩一区二区| 亚洲色图 男人天堂 中文字幕| 久久久久久伊人网av| 日日爽夜夜爽网站| 婷婷成人精品国产| 久久久久国产网址| 成人手机av| 中文字幕最新亚洲高清| 男人爽女人下面视频在线观看| 如何舔出高潮| 侵犯人妻中文字幕一二三四区| 久久国产精品大桥未久av| 亚洲国产精品999| 久久久久精品人妻al黑| 欧美最新免费一区二区三区| 亚洲欧美一区二区三区黑人 | 黑丝袜美女国产一区| 99精国产麻豆久久婷婷| 精品福利永久在线观看| 婷婷色麻豆天堂久久| 国产有黄有色有爽视频| 一级毛片 在线播放| 久久99热这里只频精品6学生| 免费黄色在线免费观看| 1024香蕉在线观看| 伊人亚洲综合成人网| 精品午夜福利在线看| 大片免费播放器 马上看| 18禁观看日本| 国产精品一区二区在线观看99| 美女主播在线视频| 日本爱情动作片www.在线观看| 少妇人妻精品综合一区二区| 国产成人一区二区在线| 国产熟女午夜一区二区三区| 美女xxoo啪啪120秒动态图| 亚洲欧美中文字幕日韩二区| 考比视频在线观看| 亚洲精品日韩在线中文字幕| xxx大片免费视频| 超碰成人久久| 日本91视频免费播放| 90打野战视频偷拍视频| 视频区图区小说| 高清av免费在线| 久久影院123| 一区二区三区乱码不卡18| 免费少妇av软件| 日产精品乱码卡一卡2卡三| 午夜福利视频精品| 热99久久久久精品小说推荐| 欧美人与性动交α欧美精品济南到 | 777久久人妻少妇嫩草av网站| 欧美黄色片欧美黄色片| 日韩中文字幕视频在线看片| 丝袜在线中文字幕| 制服丝袜香蕉在线| xxxhd国产人妻xxx| 久久久国产欧美日韩av| 亚洲av中文av极速乱| 天美传媒精品一区二区| 日本欧美视频一区| 亚洲美女视频黄频| 99热全是精品| 国产精品.久久久| 自拍欧美九色日韩亚洲蝌蚪91| 侵犯人妻中文字幕一二三四区| 久久久久国产网址| 欧美日韩亚洲国产一区二区在线观看 | 亚洲美女视频黄频| 欧美人与性动交α欧美软件| 另类亚洲欧美激情| 亚洲av.av天堂| 狂野欧美激情性bbbbbb| 欧美激情极品国产一区二区三区| www.熟女人妻精品国产| 黄色 视频免费看| 午夜福利视频在线观看免费| 国产精品久久久av美女十八| 国产精品.久久久| 波多野结衣一区麻豆| 人妻人人澡人人爽人人| 午夜福利,免费看| av片东京热男人的天堂| 一区二区三区激情视频| 亚洲av日韩在线播放| 免费观看性生交大片5| 久久久a久久爽久久v久久| 男女免费视频国产| 国精品久久久久久国模美| 免费黄频网站在线观看国产| 如日韩欧美国产精品一区二区三区| 99九九在线精品视频| 国产又色又爽无遮挡免| 亚洲精品乱久久久久久| 丝袜在线中文字幕| 最新的欧美精品一区二区| 精品第一国产精品| 国产免费又黄又爽又色| 亚洲国产av新网站| 啦啦啦啦在线视频资源| 男女下面插进去视频免费观看| 免费观看性生交大片5| 天天影视国产精品| 欧美日韩一级在线毛片| 9191精品国产免费久久| 老熟女久久久| 国产高清不卡午夜福利| 性少妇av在线| 亚洲精品第二区| 波野结衣二区三区在线| 欧美精品av麻豆av| 老女人水多毛片| 成人黄色视频免费在线看| 免费日韩欧美在线观看| 亚洲av电影在线进入| 一本—道久久a久久精品蜜桃钙片| 亚洲精品国产av成人精品| 少妇精品久久久久久久| 永久网站在线| av天堂久久9| 亚洲精品中文字幕在线视频| 精品少妇黑人巨大在线播放| 免费播放大片免费观看视频在线观看| 午夜91福利影院| 亚洲欧美成人精品一区二区| 免费女性裸体啪啪无遮挡网站| 国产成人免费观看mmmm| av女优亚洲男人天堂| 亚洲精品久久成人aⅴ小说| 日韩av不卡免费在线播放| 9色porny在线观看| 国产精品嫩草影院av在线观看| 免费少妇av软件| 国产熟女欧美一区二区| av网站在线播放免费| 亚洲精品成人av观看孕妇| 美女高潮到喷水免费观看| 国产成人91sexporn| 久久久久精品性色| 九草在线视频观看| 少妇的丰满在线观看| 人妻少妇偷人精品九色| 国产又色又爽无遮挡免| 欧美最新免费一区二区三区| 极品人妻少妇av视频| 免费日韩欧美在线观看| 蜜桃在线观看..| 欧美日韩视频精品一区| 咕卡用的链子| 精品一品国产午夜福利视频| 婷婷色综合大香蕉| 国语对白做爰xxxⅹ性视频网站| 亚洲视频免费观看视频| 少妇被粗大猛烈的视频| 我要看黄色一级片免费的| 国产成人精品一,二区| 人成视频在线观看免费观看| 少妇人妻久久综合中文| a级毛片黄视频| 国产成人午夜福利电影在线观看| 波多野结衣一区麻豆| 咕卡用的链子| 成年女人在线观看亚洲视频| 国产成人精品无人区| www.熟女人妻精品国产| 纯流量卡能插随身wifi吗| 国产熟女欧美一区二区| 中文精品一卡2卡3卡4更新| 侵犯人妻中文字幕一二三四区| 精品人妻熟女毛片av久久网站| 日日撸夜夜添| 少妇人妻精品综合一区二区| 在线精品无人区一区二区三| 制服诱惑二区| 亚洲一区中文字幕在线| 熟女电影av网| 亚洲国产最新在线播放| 在线天堂中文资源库| 国产亚洲最大av| 亚洲第一av免费看| 日日撸夜夜添| 国产成人欧美| 亚洲美女黄色视频免费看| 777久久人妻少妇嫩草av网站| 黑丝袜美女国产一区| 人人澡人人妻人| 美女午夜性视频免费| 黄片无遮挡物在线观看| 国产乱来视频区| 精品福利永久在线观看| 男人爽女人下面视频在线观看| 一级毛片黄色毛片免费观看视频| 99九九在线精品视频| 日本黄色日本黄色录像| 欧美日韩视频高清一区二区三区二| 成人午夜精彩视频在线观看| 日韩三级伦理在线观看| 少妇熟女欧美另类| 午夜福利一区二区在线看| 国产精品 国内视频| 青春草亚洲视频在线观看| 妹子高潮喷水视频| 五月开心婷婷网| 制服诱惑二区| 亚洲综合精品二区| 久久毛片免费看一区二区三区| 26uuu在线亚洲综合色| 啦啦啦啦在线视频资源| 91国产中文字幕| 黄色视频在线播放观看不卡| 久久人妻熟女aⅴ| 午夜91福利影院| 性高湖久久久久久久久免费观看| av卡一久久| 99国产精品免费福利视频| 国产高清国产精品国产三级| 18禁国产床啪视频网站| 国产视频首页在线观看| 午夜福利乱码中文字幕| 午夜久久久在线观看| 天天影视国产精品| 一边亲一边摸免费视频| 成年动漫av网址| 日韩中文字幕视频在线看片| 青春草视频在线免费观看| 久久久久视频综合| 免费少妇av软件| 中文字幕色久视频| 波多野结衣av一区二区av| 成人国产麻豆网| 久久久久久久国产电影| 欧美日韩成人在线一区二区| 99久久综合免费| 欧美97在线视频| 在线观看免费日韩欧美大片| 亚洲精品久久午夜乱码| 亚洲少妇的诱惑av| 最新的欧美精品一区二区| 9热在线视频观看99| 国产免费福利视频在线观看| 丝袜脚勾引网站| 国产女主播在线喷水免费视频网站| 久久国内精品自在自线图片| 精品福利永久在线观看| 亚洲欧美一区二区三区国产| 欧美日韩成人在线一区二区| 精品少妇一区二区三区视频日本电影 | 国产亚洲av片在线观看秒播厂| 少妇被粗大猛烈的视频| 久久久久久人妻| 久久久精品国产亚洲av高清涩受| 九九爱精品视频在线观看| 99香蕉大伊视频| 久久久久久久国产电影| 搡女人真爽免费视频火全软件| 亚洲国产成人一精品久久久| 亚洲国产av影院在线观看| 在线亚洲精品国产二区图片欧美| 搡女人真爽免费视频火全软件| 伊人久久大香线蕉亚洲五| 免费播放大片免费观看视频在线观看| 十八禁高潮呻吟视频| 亚洲综合色惰| 久久久久久久亚洲中文字幕| 高清av免费在线| 亚洲三级黄色毛片| 免费av中文字幕在线| 亚洲人成网站在线观看播放| 久久ye,这里只有精品| 尾随美女入室| 色视频在线一区二区三区| 亚洲久久久国产精品| 亚洲 欧美一区二区三区| 亚洲久久久国产精品| 人人妻人人添人人爽欧美一区卜| 在线天堂中文资源库| 免费观看无遮挡的男女| 久久精品人人爽人人爽视色| 午夜老司机福利剧场| 欧美最新免费一区二区三区| 中文字幕精品免费在线观看视频| 国产成人精品久久二区二区91 | 婷婷成人精品国产| 建设人人有责人人尽责人人享有的| 久久精品亚洲av国产电影网| 精品99又大又爽又粗少妇毛片| 成人国产麻豆网| 视频区图区小说| 美女视频免费永久观看网站| 亚洲欧美精品自产自拍| 亚洲,一卡二卡三卡| 天天影视国产精品| 久久这里只有精品19| 又黄又粗又硬又大视频| 深夜精品福利| 亚洲国产欧美在线一区| 晚上一个人看的免费电影| 制服丝袜香蕉在线| 青青草视频在线视频观看| 97在线人人人人妻| 亚洲精品自拍成人| 超碰成人久久| 赤兔流量卡办理| 国产一区亚洲一区在线观看| 免费看av在线观看网站| 永久免费av网站大全| 日本爱情动作片www.在线观看| 久久婷婷青草| 日韩一卡2卡3卡4卡2021年| 亚洲国产精品成人久久小说| 岛国毛片在线播放| 欧美日韩视频高清一区二区三区二| h视频一区二区三区| 一级毛片 在线播放| 久久久精品区二区三区| 寂寞人妻少妇视频99o| 精品少妇久久久久久888优播| 男女无遮挡免费网站观看| 亚洲av成人精品一二三区| 一区二区三区激情视频| 中文字幕人妻丝袜制服| 中文字幕av电影在线播放| 国产xxxxx性猛交| 精品久久久精品久久久| 激情视频va一区二区三区| 中文欧美无线码| 亚洲国产成人一精品久久久| 国产成人免费观看mmmm| 两个人免费观看高清视频| 成人国语在线视频| 自线自在国产av| 国产精品国产三级专区第一集| 亚洲欧美清纯卡通| 捣出白浆h1v1| 男女国产视频网站| 18禁国产床啪视频网站| 日本av手机在线免费观看| 久久久久久久久久久免费av| www日本在线高清视频| 男的添女的下面高潮视频| 一边摸一边做爽爽视频免费| 亚洲天堂av无毛| 免费黄网站久久成人精品| 国产一区亚洲一区在线观看| 日韩欧美一区视频在线观看| 观看美女的网站| 亚洲成人av在线免费| 国产精品嫩草影院av在线观看| 免费高清在线观看视频在线观看| 欧美 日韩 精品 国产| 色婷婷av一区二区三区视频| 久久精品熟女亚洲av麻豆精品| 制服人妻中文乱码| 性高湖久久久久久久久免费观看| 成年人午夜在线观看视频| 男的添女的下面高潮视频| 热99国产精品久久久久久7| 美女脱内裤让男人舔精品视频| 久久影院123| 成年女人在线观看亚洲视频| 成人国语在线视频| 久久久久久久大尺度免费视频| 欧美亚洲 丝袜 人妻 在线| 国产老妇伦熟女老妇高清| 老司机影院毛片| 国产免费视频播放在线视频| 国产探花极品一区二区| 天美传媒精品一区二区| 亚洲视频免费观看视频| 色哟哟·www| h视频一区二区三区| xxx大片免费视频| 久久久a久久爽久久v久久| 极品人妻少妇av视频| 久久人人97超碰香蕉20202| 日本午夜av视频| 国产精品久久久久久久久免| 国产精品成人在线| 999精品在线视频| av在线观看视频网站免费| 欧美成人午夜精品| 婷婷色综合大香蕉| 国产成人精品一,二区| 亚洲情色 制服丝袜| 女性生殖器流出的白浆| 777久久人妻少妇嫩草av网站| 成人黄色视频免费在线看| 欧美av亚洲av综合av国产av | 久久午夜综合久久蜜桃| 伦理电影大哥的女人| 国产老妇伦熟女老妇高清| 亚洲天堂av无毛| tube8黄色片| 久久久久人妻精品一区果冻| 欧美最新免费一区二区三区| 国产黄色视频一区二区在线观看| 视频区图区小说| 国产淫语在线视频| 久久 成人 亚洲| 高清黄色对白视频在线免费看| 丰满饥渴人妻一区二区三| 精品一区二区免费观看| 欧美变态另类bdsm刘玥| 卡戴珊不雅视频在线播放| 国产成人精品久久久久久| 欧美成人午夜精品| 99久久中文字幕三级久久日本| 考比视频在线观看| 亚洲国产欧美网| 国产精品 国内视频| 在线亚洲精品国产二区图片欧美| 午夜久久久在线观看| 黄色配什么色好看| 亚洲国产精品成人久久小说| 欧美日韩一级在线毛片| 男女无遮挡免费网站观看| 高清不卡的av网站| 成人毛片a级毛片在线播放| 18禁观看日本| www.精华液| 国产成人精品在线电影| 久久精品夜色国产| 亚洲国产av新网站| 熟女av电影| 精品久久久精品久久久| 91aial.com中文字幕在线观看| 午夜福利视频在线观看免费| 日韩成人av中文字幕在线观看| 中文字幕人妻丝袜制服| 国产精品久久久久久久久免| 午夜激情久久久久久久| 成人免费观看视频高清| 欧美日韩av久久| 国产国语露脸激情在线看| 日韩一区二区视频免费看| 国精品久久久久久国模美| 叶爱在线成人免费视频播放| 又黄又粗又硬又大视频| 亚洲av欧美aⅴ国产| 97人妻天天添夜夜摸| 精品人妻偷拍中文字幕| 少妇 在线观看| 久久99蜜桃精品久久| 国产精品久久久久久久久免| 免费在线观看黄色视频的| www.自偷自拍.com| 极品人妻少妇av视频| 久久久欧美国产精品| 最近手机中文字幕大全| 日本av免费视频播放| 日韩精品免费视频一区二区三区| 亚洲色图综合在线观看| 日韩一本色道免费dvd| 亚洲精品一区蜜桃| 国产片内射在线| 99精国产麻豆久久婷婷| 激情视频va一区二区三区| 啦啦啦在线观看免费高清www| www.av在线官网国产| 亚洲精品第二区| 国产97色在线日韩免费| 国产在线视频一区二区| a级毛片黄视频| 亚洲欧洲国产日韩| 1024香蕉在线观看| 又黄又粗又硬又大视频| 欧美bdsm另类| 另类亚洲欧美激情| 高清欧美精品videossex| 哪个播放器可以免费观看大片| 一区二区日韩欧美中文字幕| 午夜日韩欧美国产| 亚洲美女黄色视频免费看| 精品国产一区二区三区四区第35| av卡一久久| 免费人妻精品一区二区三区视频| 日韩视频在线欧美| 亚洲精品av麻豆狂野| 麻豆av在线久日| 国产日韩欧美在线精品| 国产成人免费无遮挡视频| 欧美日韩成人在线一区二区| 国产成人精品一,二区| 亚洲成人手机| 一区二区三区精品91| 亚洲国产看品久久| 嫩草影院入口| 天天操日日干夜夜撸|