• <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 ?

    Synthesis and characterizations of boron and nitrogen co-doped high pressure and high temperature large single-crystal diamonds with increased mobility*

    2021-06-26 03:30:42XinYuanMiao苗辛原HongAnMa馬紅安ZhuangFeiZhang張壯飛LiangChaoChen陳良超LiJuanZhou周麗娟MinSiLi李敏斯andXiaoPengJia賈曉鵬
    Chinese Physics B 2021年6期
    關(guān)鍵詞:紅安

    Xin-Yuan Miao(苗辛原)Hong-An Ma(馬紅安) Zhuang-Fei Zhang(張壯飛) Liang-Chao Chen(陳良超)Li-Juan Zhou(周麗娟) Min-Si Li(李敏斯) and Xiao-Peng Jia(賈曉鵬)

    1College of Physics,Guangxi University of Science and Technology,Liuzhou 545006,China

    2State Key Laboratory of Superhard Materials,College of Physics,Jilin University,Changchun 130012,China

    3Key Laboratory of Material Physics of Ministry of Education,and School of Physical Engineering,Zhengzhou University,Zhengzhou 450052,China

    Keywords: high pressure and high temperature(HPHT),diamond,growth of crystal,boron and nitrogen codoped diamond

    1. Introduction

    Nitrogen and boron are the most familiar impurities in synthesized diamonds by high pressure and high temperature(HPHT). As a shallow energy level acceptor, boron impurity in diamond has an ionization energy of 0.37 eV and can be activated at room temperature.[1]So boron-doped diamond(BDD)is considered as a promising p-type semiconductor material, which has many outstanding properties such as high hardness, high thermal conductivity, and high mobility.[2–4]As the boron concentration in BDD increases, the acceptor ionization energy decreases because the acceptor energy levels increase and merge into energy band. The BDD films present a metal–insulator transition for a boron concentration on the order of 4.5×1020cm?3.[5]Superconductivity in diamond can even be observed in some heavily boron-doped diamond films and growth surface of heavily HPHT single-crystal diamonds when the boron concentration increases to the order of 1021cm?3.[6,7]However, the boron concentration threshold is not often reached because of the compensating nitrogen donors.[8]In BDD with boron concentration below the threshold of metal–insulator transition,just only a small part(about 1%–2%)of total boron atoms can be ionized.[8]As the investigation of Pernot,the low carrier mobility in BDD with high boron concentration (below the threshold of metal–insulator transition)is attributed to the scattering mechanism caused by the dominant neutral boron acceptors, i.e., neutral impurity(ni).[9]And the ni mode could be the main factor limiting the mobility and conductivity in BDD.

    Nitrogen has a very high solubility in diamond and it enters the diamond lattice as a substitutional impurity in the process of crystal growth both by HPHT and CVD.[10–12]As a typical deep donor in diamond, nitrogen impurity can hardly be ionized at room temperature,but can easily compensate boron acceptors and decrease the concentration of neutral boron impurity.[8,13]The nitrogen and boron co-doping of CVD diamond films and HPHT diamonds has been studied by some groups. The improvements on electron field emission properties and mechanical properties, and some variations of optical characterization were also observed in previous reports.[14–17]Nevertheless,the reports concentrated on the nitrogen and boron co-doping of HPHT large single-crystal diamonds are scarce. There are only a few relevant reports in which the diamonds present very poor electrical property due to the low boron concentration.[14,17,18]In this paper, borondoped single-crystal diamonds(BDD)and boron/nitrogen codoped single-crystal diamonds (BNDD) with low resistivity and increased mobility were synthesized by HPHT,and the effects of nitrogen incorporation on optical and electrical properties of BDD and BNDD were investigated.

    2. Experimental details

    The synthetic diamonds in this study were grown on a{111}face of seed by the temperature gradient growth(TGG) method in Fe–Ni–C–B environments under 5.9 GPa and 1290°C using a China-type large-volume cubic high pressure apparatus (CHPA) (SPD-6×1200). A schematic diagram of the cell assembly used for crystal growth is shown in Fig.1(a).

    High-purity graphite was used as the carbon source and high-purity amorphous boron powder was used as the boron source. Ti was used as the nitrogen getter in the growth system to synthesize BDD. NaN3powder was used as the nitrogen source to synthesize BNDD. We grew the diamonds with different boron and nitrogen concentrations by means of changing the corresponding additive contents (weight ratio to carbon source) in the original growth systems. The specific information of doping is listed in Table 1. The asgrown diamonds presented octahedral habitus and were cut into the{111}square plates with a thickness of about 0.4 mm by laser. The plates were polished and cleaned by the boiling concentrated sulfuric acid and alcohol successively before characterization. The{111}surface of the as-grown samples were observed by scanning electron microscope (SEM).The plate samples were characterized by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy(FTIR),and Raman spectroscopy. The Hall effect of the plates samples was measured using the van der Pauw four-probe method at room temperature, and Ag was used as the electrode.

    Fig. 1. (a) Assembly of high-pressure chamber: 1. pyrophyllite; 2.conductive rim; 3. cooper sheet; 4. graphite; 5. dolomite; 6. thermal insulation material; 7. carbon source; 8. catalyst alloy; 9. insulating material; 10. seed; 11. as-grown crystal. (b) As-grown diamond of BDD-1. (c){111}square plate sample BDD-1.

    3. Results and discussion

    All the grown crystals are opaquely black octahedral diamonds.In order to observe the effect of nitrogen on the surface morphology of boron-doped diamonds,the{111}surfaces of original samples BDD-2 and BNDD-2 were characterized by SEM.As shown in Fig.2,the growth surfaces of two diamonds are not smooth. There are a lot of triangular step growth defects with different sizes on the{111}surface of boron-doped samples BDD-2 and all the triangular defects have the regular orientation and uniform angle of 60°consistent with angles of the{111}surface. The orientation should be the direction of carbon atoms stacking in the growth layer. As incorporation of nitrogen,the surface morphology of BNDD-2 is distinctive.The crystal surfaces,not only{111}surface,are covered with obviously dentritic defects and no triangular step defects are observed. We consider that such dentritic defects could not be growth traces of crystals,but generated in process of condensing of molten metallic catalyst while the diamonds no longer grow. The dentritic defects were also observed in nitrogen and boron co-doped diamonds grown in a system with h-BN additive in previous report.[14]It could be relevant to abundant nitrogen and boron impurities in the growth system.

    Fig.2. SEM images of{111}growth surfaces of samples BDD-2 and BNDD-2.

    Fig.3. (a)XPS spectra of boron doped diamond(BDD-2)and boron/nitrogen co-doped diamond(BNDD-2). The two spectra are the amplification of N 1s peaks of(b)BDD-2 and(c)BNDD-2.

    In such boron-rich large single-crystal diamonds, nitrogen hardly can be tested by regular FTIR methods. In order to study the states of nitrogen impurity in BDD and BNDD diamonds, the samples BDD-2 and BNDD-2 were tested by XPS. As shown in Fig. 3, beside the C 1s peak, both XPS spectra show obvious O 1s peak which may be the result of surface oxidation. The N 1s peak is very intensive in sample BNDD-2,nevertheless hardly observable in sample BDD-2. It shows a good evidence that nitrogen impurity has been incorporated into the boron-doped diamond lattice by the additive in the growth system. The N 1s peak of BDD-2 can be deconvoluted into two peaks with the binding energies of 399.3 eV and 400.0 eV,which are assigned to the sp3N–C bonding and the long N–C bond, respectively. And the N 1s peak of BNDD-2 can not be separated and present a strong peak at 399.3 eV assigned to sp3N–C bonding.[19–21]

    We did not observed the peak relating to B–N bond in XPS result of co-doped diamond(BNDD-2). However,it can not be concluded that there is no B–N bond existing in such diamond, because the complicated circumstance of impurity in the co-doped diamond affects detecting significantly. Theoretical researches demonstrated that B–N dimer impurity in diamond has a negative formation energy of?0.17 eV.[22,23]It indicates that B–N dimer impurity is a very stable compound impurity and a potentially present cluster in multiple types of diamonds,especially in boron and nitrogen co-doped diamonds. We believe the bonding of B–N exists in such diamonds,despite the fact we did not detect them.

    Raman spectroscopy is essential and familiar in borondoped diamond research because it provides abundant information relevant to boron impurity and properties of diamonds.The Raman peak of diamond at 1332 cm?1(the zone-center optical phonon line) shifts with the variation in property of diamonds, e.g., tensile stress in diamond leading to redshift of diamond Raman peak. The full width at half maximum(FWHM) of the diamond peak is also considered to be related to crystallinity(narrower FWHM corresponds to higher crystallinity).[24]

    Samples were tested by Raman spectroscopy with an excitation source of 532 nm at room temperature. Raman spectra of the as-grown surfaces and interiors (polished surfaces)of four diamonds are shown in Figs. 4(a) and 4(b), no peaks due to amorphous carbon or graphite phase were detected.The diamond peak position (Xc) and FWHM of the Raman peaks of interiors of samples were compared and listed in the insert of Fig.4(a). From the Raman results, it is found that the increase of boron additive in the growth system leads to redshift ofXc(from 1332.01 cm?1to 1330.34 cm?1)and broadening of FWHM(from 4.39 cm?1to 6.36 cm?1). In BNDD-1 and BNDD-2, the incorporation of nitrogen impurity leads to shift ofXcto the higher wavenumber(from 1330.34 cm?1to 1331.00 cm?1)and the narrowing of FWHM(from 6.36 cm?1to 4.14 cm?1). It seems that boron and nitrogen co-doped diamonds have better crystallization than boron doped diamonds.

    Differing from other doping elements in diamonds,boron impurity allows some forbidden states to exist in Raman spectroscopy. As shown in Figs. 4(a) and 4(b), a series of additional bands at 580 cm?1, 900 cm?1, and 1042 cm?1can be observed in the Raman spectra, which is related to the defect-induced activity of density of phonon states (DOS) of diamonds.[25]These bands are frequently observed in diamond with high boron concentration, barely found in low boron doped diamonds.[24–26]In Raman spectra of the as-grown surfaces shown in Fig. 4(b), spectra of BDD-1, BNDD1, and BNDD-2 present evident features of these bands (identical with features of interiors of diamonds). Such additional bands indicate that the samples have high boron concentration but still below the threshold of metal–insulator transition level.[6,7]The Raman spectrum of surface of sample BDD-2 shows distinct features of “500 cm?1band” located at 470 cm?1, the shift is due to the higher boron concentration in the diamond surface. The appearance of the 500 cm?1band means that the concentration of boron reaches heavily doped level, and the band was attributed to boron dimer on diamond surface.[6,7]The difference between Raman spectra on surface and interior of BDD-2 comes from the difference of boron concentration.Boron impurity has an upper limit of solubility in diamond lattice,however is more likely to bond with carbon atoms(even form boron dimer)on the surface because of abundant vacancy on as-grown surface,so as to achieve higher boron concentration on surface of diamond.

    The asymmetry of 1332 cm?1diamond peak was frequently observed in highly and heavily boron doped diamonds,which is attributed to the Fano effect (a quantum interaction between discrete zone center Raman phonon and transitions from impurity band to continuum state composed of excited acceptor states and valence band)and is called Fano line shape.[27–30]Generally, the increasing boron concentration in diamond intensifies the Fano effect in Raman spectroscopy.As shown in Fig. 4(b), the asymmetry is very evident in spectra of the first three samples, comparatively weaker in spectra of BNDD-2.This indicates that the Fano effect was weakened by incorporation of nitrogen impurity in boron doped diamonds.

    Fig.4. (a)Raman spectra of interiors of samples BDD-2 and BNDD-1,the insert shows fitting curves of 1332 cm?1 peak of all four samples.(b) Raman spectra of as-grown surfaces of four samples. Peak “DIAMOND” is the diamond Raman peak (the zone-center optical phonon line)and the lines were moved vertically for clarity.

    The infrared spectra of four polished diamond crystals are shown in Fig. 5. The band of 1290 cm?1originates from the one-phonon-absorption of boron impurities in diamond,corresponding to the phonon energy of 160 meV. Peaks at 2460 cm?1, 2800 cm?1, and 2927 cm?1, as shown in the spectrum of BNDD-2, correspond to transitions to the first,second, and third excited states of the bound hole, corresponding to activation energies of 304 meV, 347 meV, and 363 meV,respectively.[31–33]The infrared spectrum of BNDD-2 belongs to the typical infrared spectra of synthesized boron doped diamonds.[31,33]However, in the spectrum of BDD-1,the three peaks assigned to the transitions of bound hole are hardly observable because of photoionization continuum. The photoionization continuum, which generally starts at around 370 meV (activation energy of boron acceptor), is phononrepeated and extends well into the visible.It is also responsible for the bluish color of type IIb diamonds.[1,31]As the increase of boron acceptor concentration in diamonds, the wave functions of adjacent B atoms overlap, the photoionization continuum intensifies and threshold shifts to the direction of low energy.[33,34]

    Fig.5. FTIR absorption spectra of boron doped diamonds(BDD-1 and BDD-2)and boron/nitrogen co-doped diamonds(BNDD-1 and BNDD-2)(a)and the amplification of spectra of BDD-2 and BNDD-1(b). The curves were moved vertically for clarity.

    Therefore, the infrared spectra of BDD-2 and BNDD-1 with higher boron concentration are overwhelmed by photoionization continuum, no obvious B-related absorption peaks are found, typical highly B-doped diamond infrared spectra.[8]In addition,the 1290 cm?1band and a slight declination of photoionization continuum at low energy region can be observed in the spectrum of BNDD-1. It indicates that the boron concentration in sample BNDD-1 slightly decreases as the incorporation of nitrogen. Thus,based on analysis above,the infrared spectra present a convincing semi-quantitative picture of the effects of the interaction of boron and nitrogen in HPHT synthesized diamonds. We find that the concentration of boron acceptor in the diamond increases with the increasing boron additive content in the growth system,and decreases with the incorporation of nitrogen impurity. This is probably due to changes in the composition of the growth catalyst caused by nitrogen-containing additive affecting concentration of boron and nitrogen in the diamond lattice,and due to compensation of nitrogen donors for boron acceptors in the diamond lattice.

    The Hall effect of samples was measured at room temperature by the four-probe method. The results are listed in Table 1. All samples exhibit p-type semiconducting properties,and the sample BDD-2 has the lowest resistivity of 0.9 ?·cm and the highest carrier concentration of 7.4×1017cm?3at room temperature.The mobility of samples BDD-1 and BDD-2 is very low, because the mobility of samples BDD-1 and BDD-2 is mainly limited by the scattering caused by the neutral boron impurities. As the investigation of Hall hole mobility in boron-doped diamond by Pernotet al.,[9]in BDD semiconductors with high boron concentration(below the threshold of metal–insulator transition),electrical neutral boron impurities play a major role in carrier scattering,which is considered to be the main reason for limiting the conductivity of borondoped diamonds with high boron concentration. The carrier concentration of BNDD-1 and BNDD-2 samples is much lower than that of the first two samples, which could be due to the increasing activation energy caused by the lower boron concentration and nitrogen compensating for the boron acceptor in the crystal. However, it is interesting to found that the mobility of BNDD-1 and BNDD-2 is much higher than that of BDD-1 and BDD-2. The highest mobility of sample BNDD-1 reached 980 cm2·V?1·s?1. Two factors are considered to account for the increase in mobility of boron/nitrogen co-doped samples.(I)As the results of Raman spectroscopy,the samples of BNDD have better crystallinity than BDD, which benefits the carriers mobility in diamonds. (II)As the results of FTIR spectra,the incorporation of nitrogen obviously decreases the boron impurity concentration, especially dominant unionized neutral boron atoms,which is responsible for the low mobility in boron-doped diamonds.

    Table 1. Conditions of additives in growth system and Hall measurement results. ρ is the resistivity;μ is the Hall mobility,and n is the density of free carriers.

    4. Conclusions

    In summary, boron doped diamonds and boron/nitrogen co-doped single-crystal diamonds with low electrical resistivity were synthesized by temperature gradient growth method under HPHT conditions. SEM, XPS, Raman and FTIR of boron doped and boron/nitrogen co-doped diamonds were analyzed. The results of FTIR spectroscopy present a semiquantitative picture of the effects of the interaction of boron and nitrogen in HPHT synthesized diamonds. The results of Hall effect show that all samples present p-type conductivity.Boron and nitrogen co-doped diamonds present lower carrier concentration,but higher mobility than boron doped diamonds as incorporation of nitrogen. We consider that the increase in mobility may probably be attributed to the decreased neutral boron impurity level and the improvement of crystallinity.The results would be useful for further investigations about electrical properties of HPHT single crystal and co-doping of diamonds in the future.

    猜你喜歡
    紅安
    紅安紅秀劇場(chǎng)演繹“紅安紅”
    Diamond growth in a high temperature and high pressure Fe-Ni-C-Si system: Effect of synthesis pressure
    Effect of the codoping of N–H–O on the growth characteristics and defects of diamonds under high temperature and high pressure
    紅安精神研究述評(píng)
    新疆天椒紅安農(nóng)業(yè)科技有限責(zé)任公司
    辣椒雜志(2021年4期)2021-04-14 08:28:12
    Utilizing of high-pressure high-temperature synthesis to enhance the thermoelectric properties of Zn0.98Al0.02O with excellent electrical properties*
    紅安頌
    紅安脫貧摘帽喜賦
    Synthesis of diamonds in Fe C systems using nitrogen and hydrogen co-doped impurities under HPHT?
    饒惠熙
    亚洲三区欧美一区| 真人做人爱边吃奶动态| 窝窝影院91人妻| 中文字幕高清在线视频| 欧美成人午夜精品| 日韩欧美一区视频在线观看| www.999成人在线观看| a级毛片在线看网站| 欧美一级毛片孕妇| 757午夜福利合集在线观看| 最好的美女福利视频网| 国内毛片毛片毛片毛片毛片| 夜夜夜夜夜久久久久| 午夜成年电影在线免费观看| 91精品国产国语对白视频| 999久久久精品免费观看国产| 亚洲专区中文字幕在线| 长腿黑丝高跟| 午夜免费激情av| www.精华液| 欧美精品啪啪一区二区三区| 男人舔女人下体高潮全视频| 国产精品自产拍在线观看55亚洲| 免费在线观看亚洲国产| 国产精品野战在线观看| 国产精品久久久久久亚洲av鲁大| 国产精品免费一区二区三区在线| 两性夫妻黄色片| av天堂久久9| 九色亚洲精品在线播放| 在线永久观看黄色视频| 男人的好看免费观看在线视频 | 国产色视频综合| 在线播放国产精品三级| 日韩中文字幕欧美一区二区| 美女高潮喷水抽搐中文字幕| 别揉我奶头~嗯~啊~动态视频| 亚洲情色 制服丝袜| 又紧又爽又黄一区二区| 国产欧美日韩一区二区三| 中亚洲国语对白在线视频| 亚洲国产精品久久男人天堂| 亚洲色图av天堂| 精品国产一区二区三区四区第35| 亚洲国产欧美一区二区综合| 制服人妻中文乱码| 久久精品aⅴ一区二区三区四区| 90打野战视频偷拍视频| 成人国语在线视频| 国产成+人综合+亚洲专区| 亚洲av成人不卡在线观看播放网| 黄色视频,在线免费观看| 美女 人体艺术 gogo| 精品国内亚洲2022精品成人| 久久婷婷成人综合色麻豆| 国产精品久久久人人做人人爽| 国产成人精品在线电影| 日本撒尿小便嘘嘘汇集6| 9191精品国产免费久久| 色在线成人网| 一个人观看的视频www高清免费观看 | 脱女人内裤的视频| 女人高潮潮喷娇喘18禁视频| 少妇裸体淫交视频免费看高清 | 亚洲七黄色美女视频| 91麻豆av在线| 在线观看66精品国产| 黄色女人牲交| 99在线视频只有这里精品首页| 50天的宝宝边吃奶边哭怎么回事| 18禁观看日本| 90打野战视频偷拍视频| 女人精品久久久久毛片| 精品福利观看| 亚洲久久久国产精品| 香蕉国产在线看| 免费观看精品视频网站| 91成人精品电影| 日本a在线网址| 亚洲一区高清亚洲精品| 国产精品1区2区在线观看.| 国产免费av片在线观看野外av| 日韩大码丰满熟妇| 国产精品野战在线观看| 巨乳人妻的诱惑在线观看| 亚洲七黄色美女视频| 美女扒开内裤让男人捅视频| 在线观看www视频免费| 天堂动漫精品| 97超级碰碰碰精品色视频在线观看| 亚洲一区二区三区不卡视频| 精品久久久久久,| 久久久久久久精品吃奶| 欧美大码av| 亚洲欧美激情在线| videosex国产| 亚洲精品国产一区二区精华液| 亚洲专区国产一区二区| 亚洲熟妇中文字幕五十中出| 老司机午夜十八禁免费视频| 国产精品98久久久久久宅男小说| 宅男免费午夜| 午夜老司机福利片| 99国产精品一区二区三区| 国产不卡一卡二| 久久精品国产亚洲av高清一级| 久久午夜亚洲精品久久| 极品人妻少妇av视频| 成年人黄色毛片网站| 久久草成人影院| 久久国产精品人妻蜜桃| 一本大道久久a久久精品| 自线自在国产av| 老汉色av国产亚洲站长工具| 男女下面插进去视频免费观看| 91国产中文字幕| 首页视频小说图片口味搜索| 天堂影院成人在线观看| 丁香六月欧美| 亚洲专区国产一区二区| 在线视频色国产色| 亚洲av成人av| 成在线人永久免费视频| 亚洲精品久久国产高清桃花| 在线av久久热| 色综合婷婷激情| 亚洲熟女毛片儿| 麻豆成人av在线观看| 欧美一区二区精品小视频在线| 久久婷婷人人爽人人干人人爱 | 性少妇av在线| 欧美最黄视频在线播放免费| 亚洲最大成人中文| 日韩中文字幕欧美一区二区| 亚洲国产精品合色在线| 一级a爱视频在线免费观看| 亚洲av片天天在线观看| 免费少妇av软件| 中亚洲国语对白在线视频| 我的亚洲天堂| 日本五十路高清| 大型av网站在线播放| 丰满人妻熟妇乱又伦精品不卡| 不卡一级毛片| 天天添夜夜摸| 国产在线精品亚洲第一网站| 波多野结衣av一区二区av| 久久久久久久久久久久大奶| 精品一区二区三区av网在线观看| 黑人巨大精品欧美一区二区蜜桃| 高清黄色对白视频在线免费看| 久久人妻av系列| 91字幕亚洲| 男女之事视频高清在线观看| 亚洲天堂国产精品一区在线| 人人妻,人人澡人人爽秒播| 久久人妻福利社区极品人妻图片| svipshipincom国产片| 妹子高潮喷水视频| 黄频高清免费视频| 9色porny在线观看| 日本欧美视频一区| av福利片在线| 久久精品亚洲熟妇少妇任你| 亚洲熟妇熟女久久| 午夜久久久在线观看| 妹子高潮喷水视频| 日韩av在线大香蕉| 男男h啪啪无遮挡| 中文字幕人成人乱码亚洲影| 亚洲成av人片免费观看| 757午夜福利合集在线观看| 亚洲男人天堂网一区| 精品一区二区三区四区五区乱码| 久久久国产成人精品二区| 欧美激情久久久久久爽电影 | 9191精品国产免费久久| 18禁国产床啪视频网站| 性欧美人与动物交配| 女同久久另类99精品国产91| 午夜亚洲福利在线播放| 久久热在线av| 亚洲国产看品久久| 无人区码免费观看不卡| 亚洲电影在线观看av| 日韩视频一区二区在线观看| www.精华液| 少妇粗大呻吟视频| 欧美成人一区二区免费高清观看 | 18禁美女被吸乳视频| 久久人人爽av亚洲精品天堂| 啦啦啦免费观看视频1| 一区二区三区精品91| 色播在线永久视频| 欧美黄色片欧美黄色片| 国产亚洲欧美精品永久| 国产精品久久久久久亚洲av鲁大| 国产亚洲av嫩草精品影院| 国产亚洲精品一区二区www| 无遮挡黄片免费观看| 久久性视频一级片| 久久久久国产精品人妻aⅴ院| 99精品欧美一区二区三区四区| x7x7x7水蜜桃| 老司机靠b影院| 黄频高清免费视频| 波多野结衣巨乳人妻| 日韩欧美一区视频在线观看| 成人国语在线视频| 麻豆久久精品国产亚洲av| 久久精品国产亚洲av高清一级| 人妻丰满熟妇av一区二区三区| 欧美av亚洲av综合av国产av| 女警被强在线播放| 成人特级黄色片久久久久久久| 亚洲性夜色夜夜综合| 国产精品永久免费网站| 亚洲成人精品中文字幕电影| 一级作爱视频免费观看| 黑人巨大精品欧美一区二区mp4| 黑丝袜美女国产一区| 国产高清videossex| 999久久久国产精品视频| 亚洲精华国产精华精| 波多野结衣巨乳人妻| 国产av一区二区精品久久| 精品国产一区二区久久| 亚洲中文字幕一区二区三区有码在线看 | 亚洲欧美日韩高清在线视频| 免费av毛片视频| 女人精品久久久久毛片| 老司机靠b影院| 国产精品久久久久久人妻精品电影| 脱女人内裤的视频| 久久亚洲精品不卡| 久久久国产成人精品二区| 老司机靠b影院| av网站免费在线观看视频| 成人精品一区二区免费| 十八禁网站免费在线| 99久久综合精品五月天人人| 久久久久亚洲av毛片大全| 18禁裸乳无遮挡免费网站照片 | 国产视频一区二区在线看| 久久中文字幕一级| 国产成人精品久久二区二区免费| 亚洲精品美女久久久久99蜜臀| 可以免费在线观看a视频的电影网站| 亚洲成人久久性| 中亚洲国语对白在线视频| 好看av亚洲va欧美ⅴa在| 美女高潮喷水抽搐中文字幕| www.精华液| av中文乱码字幕在线| 国产亚洲av嫩草精品影院| 亚洲国产精品合色在线| 国产亚洲精品久久久久5区| 国产精品电影一区二区三区| 99热只有精品国产| 黄色丝袜av网址大全| 国产精品久久久久久亚洲av鲁大| 在线观看免费午夜福利视频| 国产午夜福利久久久久久| 免费人成视频x8x8入口观看| 欧美乱色亚洲激情| 99国产综合亚洲精品| 50天的宝宝边吃奶边哭怎么回事| 在线观看免费视频网站a站| 国产精品美女特级片免费视频播放器 | 欧美日韩亚洲综合一区二区三区_| 9色porny在线观看| 欧美老熟妇乱子伦牲交| 99久久综合精品五月天人人| 日韩成人在线观看一区二区三区| av片东京热男人的天堂| 亚洲精品在线观看二区| 国产成人av教育| 妹子高潮喷水视频| 大香蕉久久成人网| 国产亚洲精品久久久久久毛片| 狠狠狠狠99中文字幕| 亚洲国产欧美网| 男女床上黄色一级片免费看| 国产成人啪精品午夜网站| 涩涩av久久男人的天堂| 69精品国产乱码久久久| 国产一级毛片七仙女欲春2 | 欧美一级a爱片免费观看看 | 精品一品国产午夜福利视频| 大码成人一级视频| av中文乱码字幕在线| 99香蕉大伊视频| 黑人巨大精品欧美一区二区mp4| 两个人视频免费观看高清| 99久久99久久久精品蜜桃| 亚洲精品美女久久久久99蜜臀| 国产av一区在线观看免费| 美女大奶头视频| 国产麻豆69| 欧美亚洲日本最大视频资源| 两性夫妻黄色片| 侵犯人妻中文字幕一二三四区| 高清黄色对白视频在线免费看| 国产熟女xx| 琪琪午夜伦伦电影理论片6080| 黄色a级毛片大全视频| 国产av一区二区精品久久| 久久久久国产一级毛片高清牌| 精品电影一区二区在线| 中文字幕人妻熟女乱码| 999精品在线视频| 高清毛片免费观看视频网站| 亚洲中文字幕日韩| 嫁个100分男人电影在线观看| 97人妻天天添夜夜摸| 日本免费a在线| 成人精品一区二区免费| 久久久久久大精品| 国产亚洲精品综合一区在线观看 | 宅男免费午夜| 最近最新中文字幕大全电影3 | 亚洲无线在线观看| 中文字幕高清在线视频| 露出奶头的视频| 免费一级毛片在线播放高清视频 | 中文字幕精品免费在线观看视频| 日本免费a在线| 在线观看舔阴道视频| 日韩三级视频一区二区三区| 免费观看精品视频网站| 欧美激情极品国产一区二区三区| 国产成人免费无遮挡视频| 天堂√8在线中文| 久久热在线av| 1024香蕉在线观看| 国产日韩一区二区三区精品不卡| 免费在线观看完整版高清| 伦理电影免费视频| 国产一卡二卡三卡精品| 欧美久久黑人一区二区| 人人妻人人爽人人添夜夜欢视频| 怎么达到女性高潮| 天堂√8在线中文| 高潮久久久久久久久久久不卡| 99热只有精品国产| 怎么达到女性高潮| 国产精品九九99| 国产99久久九九免费精品| 日本精品一区二区三区蜜桃| 啦啦啦韩国在线观看视频| 人人妻人人爽人人添夜夜欢视频| 午夜免费鲁丝| 亚洲av美国av| 50天的宝宝边吃奶边哭怎么回事| 啦啦啦 在线观看视频| 高潮久久久久久久久久久不卡| 人人妻人人爽人人添夜夜欢视频| 一级毛片女人18水好多| 国产黄a三级三级三级人| 怎么达到女性高潮| 女性生殖器流出的白浆| 丝袜美足系列| 91av网站免费观看| 熟妇人妻久久中文字幕3abv| 国产成人精品久久二区二区91| 亚洲自偷自拍图片 自拍| 制服丝袜大香蕉在线| 国产伦一二天堂av在线观看| 两个人视频免费观看高清| 欧美日韩瑟瑟在线播放| 亚洲五月天丁香| 黄色成人免费大全| a在线观看视频网站| 国产亚洲精品久久久久久毛片| 一本久久中文字幕| 麻豆久久精品国产亚洲av| 波多野结衣一区麻豆| 色哟哟哟哟哟哟| 好男人在线观看高清免费视频 | 国产亚洲欧美在线一区二区| 午夜日韩欧美国产| 久久人妻熟女aⅴ| 一本大道久久a久久精品| 日本免费a在线| 两性午夜刺激爽爽歪歪视频在线观看 | 中文亚洲av片在线观看爽| a在线观看视频网站| 亚洲电影在线观看av| 久久性视频一级片| 18禁观看日本| 亚洲一区高清亚洲精品| 久久狼人影院| 最新美女视频免费是黄的| 亚洲男人天堂网一区| 国产成人av激情在线播放| АⅤ资源中文在线天堂| 一级毛片高清免费大全| 欧美日韩亚洲综合一区二区三区_| 国产免费男女视频| 午夜亚洲福利在线播放| 国产精品一区二区精品视频观看| 久久性视频一级片| 日韩免费av在线播放| x7x7x7水蜜桃| 一级a爱片免费观看的视频| 大码成人一级视频| 精品国产美女av久久久久小说| 制服人妻中文乱码| 久久久水蜜桃国产精品网| 99国产精品99久久久久| 免费女性裸体啪啪无遮挡网站| www日本在线高清视频| 久久精品国产亚洲av高清一级| 又黄又爽又免费观看的视频| 亚洲精品久久国产高清桃花| 国产99白浆流出| 在线观看日韩欧美| 亚洲精品一区av在线观看| 成人国语在线视频| 国产高清激情床上av| 国产av一区在线观看免费| 免费av毛片视频| 人人澡人人妻人| 国产午夜精品久久久久久| 中文字幕高清在线视频| 久久精品国产亚洲av高清一级| 国产精品99久久99久久久不卡| 国产成人影院久久av| 黄色 视频免费看| 女警被强在线播放| 亚洲国产精品999在线| www.精华液| 国产91精品成人一区二区三区| 久久人人爽av亚洲精品天堂| 91成年电影在线观看| 无限看片的www在线观看| 狠狠狠狠99中文字幕| 一级a爱视频在线免费观看| 禁无遮挡网站| 国产精品影院久久| 免费久久久久久久精品成人欧美视频| 99热只有精品国产| 精品卡一卡二卡四卡免费| 久久中文字幕人妻熟女| 久久久久久久久久久久大奶| 亚洲精品一卡2卡三卡4卡5卡| 18禁裸乳无遮挡免费网站照片 | 久久久久亚洲av毛片大全| 精品久久蜜臀av无| 国产精品香港三级国产av潘金莲| 91大片在线观看| 亚洲精品国产精品久久久不卡| 丝袜美足系列| 色播亚洲综合网| 美女国产高潮福利片在线看| 18禁裸乳无遮挡免费网站照片 | 麻豆久久精品国产亚洲av| 精品无人区乱码1区二区| 国产在线观看jvid| 久久国产精品人妻蜜桃| 久久久国产精品麻豆| 不卡av一区二区三区| 18美女黄网站色大片免费观看| 亚洲一区二区三区色噜噜| 无人区码免费观看不卡| 在线观看一区二区三区| xxx96com| 久久中文字幕人妻熟女| 侵犯人妻中文字幕一二三四区| 久久久国产成人免费| 午夜影院日韩av| svipshipincom国产片| 一二三四社区在线视频社区8| 一级毛片精品| 日日干狠狠操夜夜爽| 成年版毛片免费区| 亚洲国产欧美一区二区综合| 国产乱人伦免费视频| 香蕉国产在线看| 欧美+亚洲+日韩+国产| 久99久视频精品免费| 99久久久亚洲精品蜜臀av| x7x7x7水蜜桃| 男女做爰动态图高潮gif福利片 | 久热这里只有精品99| 啦啦啦观看免费观看视频高清 | 在线观看66精品国产| av福利片在线| 国产又色又爽无遮挡免费看| 夜夜躁狠狠躁天天躁| 黑丝袜美女国产一区| 欧美日韩精品网址| 69精品国产乱码久久久| 精品久久久久久,| 高清在线国产一区| 亚洲中文av在线| 免费在线观看视频国产中文字幕亚洲| 日韩高清综合在线| av天堂在线播放| 日本在线视频免费播放| 视频区欧美日本亚洲| 亚洲av五月六月丁香网| 中文字幕人妻熟女乱码| 亚洲国产看品久久| 啦啦啦韩国在线观看视频| 国产亚洲精品久久久久5区| 国产亚洲精品久久久久久毛片| 午夜老司机福利片| 婷婷六月久久综合丁香| 中文字幕av电影在线播放| 高清黄色对白视频在线免费看| 不卡一级毛片| 大码成人一级视频| 国产精品一区二区三区四区久久 | 国产亚洲精品久久久久久毛片| bbb黄色大片| 国产主播在线观看一区二区| 国产99久久九九免费精品| 久久精品人人爽人人爽视色| 欧美日本视频| 叶爱在线成人免费视频播放| 又黄又粗又硬又大视频| 免费看美女性在线毛片视频| 亚洲最大成人中文| 电影成人av| 欧美成人午夜精品| 夜夜夜夜夜久久久久| 国产一卡二卡三卡精品| 搡老熟女国产l中国老女人| 一本久久中文字幕| 久久国产乱子伦精品免费另类| 成人18禁高潮啪啪吃奶动态图| 99国产综合亚洲精品| 日韩中文字幕欧美一区二区| 在线av久久热| 亚洲精品美女久久久久99蜜臀| 欧美性长视频在线观看| 后天国语完整版免费观看| 精品久久久久久久久久免费视频| 一夜夜www| 国产一级毛片七仙女欲春2 | 色婷婷久久久亚洲欧美| 好男人在线观看高清免费视频 | 日韩av在线大香蕉| 亚洲 国产 在线| 多毛熟女@视频| 一个人免费在线观看的高清视频| 国产精品亚洲一级av第二区| 女人精品久久久久毛片| 男女床上黄色一级片免费看| 天天一区二区日本电影三级 | 91成人精品电影| 久久久久久久久免费视频了| 免费女性裸体啪啪无遮挡网站| 国产午夜福利久久久久久| 久久精品国产99精品国产亚洲性色 | a在线观看视频网站| 欧美日本亚洲视频在线播放| 精品一区二区三区av网在线观看| 久久精品国产亚洲av高清一级| 国产高清视频在线播放一区| 久久伊人香网站| 亚洲av电影在线进入| 侵犯人妻中文字幕一二三四区| av福利片在线| 一区二区日韩欧美中文字幕| 在线观看舔阴道视频| 给我免费播放毛片高清在线观看| 国产精品久久久av美女十八| 亚洲 欧美一区二区三区| 电影成人av| 国产男靠女视频免费网站| 9色porny在线观看| 大型av网站在线播放| 嫩草影视91久久| 最新美女视频免费是黄的| 日本免费a在线| 欧美亚洲日本最大视频资源| 熟女少妇亚洲综合色aaa.| 国产成人精品在线电影| 亚洲 欧美 日韩 在线 免费| 久久精品国产99精品国产亚洲性色 | 这个男人来自地球电影免费观看| 婷婷精品国产亚洲av在线| 国产在线精品亚洲第一网站| 亚洲av熟女| 精品电影一区二区在线| 欧美大码av| 两个人视频免费观看高清| 欧美+亚洲+日韩+国产| 亚洲天堂国产精品一区在线| 18禁美女被吸乳视频| 男人舔女人的私密视频| av天堂久久9| 两个人视频免费观看高清| 97碰自拍视频| 久久久久久久久免费视频了| 男女下面插进去视频免费观看| 亚洲av成人不卡在线观看播放网| 九色国产91popny在线| 两个人视频免费观看高清| 日韩欧美国产一区二区入口| 精品一区二区三区av网在线观看| 啪啪无遮挡十八禁网站| 亚洲少妇的诱惑av| 免费在线观看日本一区| 18美女黄网站色大片免费观看| 亚洲国产毛片av蜜桃av| 看片在线看免费视频| 91国产中文字幕| 亚洲精品久久成人aⅴ小说| 亚洲av片天天在线观看| 真人一进一出gif抽搐免费| av视频免费观看在线观看| 国产精品亚洲美女久久久|