銥襯底上異質(zhì)外延單晶金剛石: 過程與機(jī)理

王楊, 朱嘉琦, 扈忠波, 代兵

銥襯底上異質(zhì)外延單晶金剛石: 過程與機(jī)理

王楊, 朱嘉琦, 扈忠波, 代兵

（哈爾濱工業(yè)大學(xué) 復(fù)合材料與結(jié)構(gòu)研究所, 哈爾濱 150080）

金剛石因其獨特的物理化學(xué)性質(zhì), 在探測器、光電子器件等領(lǐng)域得到了廣泛的應(yīng)用, 單晶金剛石更是因為具有大幅度提高這些器件功能的潛力而引起了眾多學(xué)者的關(guān)注。目前在銥(Ir)襯底上異質(zhì)外延生長的單晶金剛石具有最大尺寸和較為優(yōu)異的生長質(zhì)量。本文介紹了可用于外延金剛石的不同結(jié)構(gòu)的襯底以及金剛石在銥(Ir)襯底上的形核和生長過程, 重點闡述了金剛石偏壓輔助形核(BEN)和外延橫向生長(ELO)的機(jī)理, 以及襯底圖形化形核生長技術(shù), 指出了目前研究存在的不足, 并對金剛石異質(zhì)外延理論和實驗研究方向進(jìn)行了展望。

單晶金剛石; 異質(zhì)外延; 偏壓輔助形核; 外延橫向生長; 綜述

金剛石是自然界中硬度最大[1]、固體材料中導(dǎo)熱率最高[2]的材料, 且具有從遠(yuǎn)紅外到近紫外寬波段光學(xué)透明[3]和負(fù)電子親和勢[4]等獨特性質(zhì), 被廣泛應(yīng)用于探測器[5-6]、散熱器件[7]、光學(xué)器件[8]和光電子器件[9]等領(lǐng)域。單晶金剛石由于具有無晶界、缺陷少、性能優(yōu)等優(yōu)點, 得到研究者越來越多的關(guān)注。

單晶金剛石的制備方法主要有高溫高壓(High Pressure High Temperature, HPHT)法和化學(xué)氣相沉積(Chemical Vapor Deposition, CVD)法[10]。HPHT法需要極高的溫度(1230~1600 ℃)和壓力(5.1~ 5.6 GPa)[11-12]條件, 制備的單晶金剛石雜質(zhì)含量較多, 且尺寸難以超過1 cm3。

CVD法包括同質(zhì)外延和異質(zhì)外延兩種。側(cè)向生長是在籽晶<100>晶面的不同側(cè)面反復(fù)外延的一種同質(zhì)外延方法, Mokuno等[13]利用側(cè)向生長法獲得了尺寸為12.6 mm×13.3 mm×3.7 mm的單晶金剛石, 但籽晶尺寸和反復(fù)生長次數(shù)都會限制金剛石的尺寸。另一種同質(zhì)外延方法是馬賽克拼接法, 利用經(jīng)Yamada等[14-15]改進(jìn)后的馬賽克拼接法可得到尺寸為40 mm×60 mm的單晶金剛石晶片, 但接縫處的生長缺陷會延伸至晶片內(nèi)部, 影響晶片質(zhì)量。

目前在銥襯底上異質(zhì)外延單晶金剛石是解決上述問題的一種可行方法。因此, 一些研究機(jī)構(gòu)和團(tuán)隊開始進(jìn)行大尺寸單晶金剛石異質(zhì)外延制備的研究, 奧格斯堡大學(xué)的Schreck等[16]在Ir(100)襯底上利用異質(zhì)外延法制備了直徑達(dá)92 mm的單晶金剛石。國內(nèi)也有高校對異質(zhì)外延法制備大尺寸單晶金剛石開展了初步實驗研究[17-20]。異質(zhì)外延單晶金剛石的技術(shù)關(guān)鍵是襯底的選擇與金剛石的形核和生長, 本文將綜述這兩個方面近年來的研究進(jìn)展, 并指出異質(zhì)外延金剛石理論和實驗中亟待解決的問題。

1 基于銥(Ir)的不同襯底結(jié)構(gòu)

一般來說, 選擇合適的金剛石異質(zhì)外延襯底需考慮襯底的物理性質(zhì)、化學(xué)性質(zhì)、晶格失配度、尺寸等因素[21]。為尋找最佳的金剛石異質(zhì)外延襯底, 研究者們研究了Si[22-24]、c-BN[25-26]、Pt[27]、Ni[28-29]、SiC[30-31]等不同材料, 圖1為在一些常用襯底上異質(zhì)外延生長的金剛石的表面形貌。從圖中可見在Ir襯底上生長的金剛石具有與單晶類似的平滑形貌, 而生長在其他襯底上的幾乎均為單一取向或近單一取向的多晶金剛石。

Ir是目前唯一可實現(xiàn)高質(zhì)量、大尺寸金剛石薄膜異質(zhì)外延的襯底材料。第一性原理計算結(jié)果表明,碳原子在Ir中的溶出能(Dissolution energy)對其濃度變化十分敏感, 當(dāng)碳原子濃度增加時, Ir襯底中的碳原子迅速失穩(wěn)析出, 該溶解–析出過程導(dǎo)致襯底表面形貌快速變化, 有利于金剛石晶粒在Ir襯底表面的平移和旋轉(zhuǎn)從而快速達(dá)到一致取向[35]。

圖1 不同襯底上異質(zhì)外延生長的金剛石的表面形貌[32-34]

(a) c-BN(001); (b) c-BN(111); (c) Al2O3(0001); (d) Ni(001); (e) Ni(111); (f) Pt(111); (g) Si(001); (h) 4H-SiC(001); (i) Ir(001)

除極少數(shù)專利使用純Ir金屬片作為襯底[36]外, 其他報道中均使用Ir薄膜作為金剛石異質(zhì)外延襯底。Ir薄膜可以利用磁控濺射[37-38]、脈沖激光沉積[39]、電子束蒸鍍[40]、分子束外延[41]等方法制備, 一般外延于MgO[42]、SrTiO3[43]和藍(lán)寶石[44]等氧化物單晶上。由于金剛石和這些金屬氧化物之間熱膨脹系數(shù)的差異, 在達(dá)到金剛石薄膜外延溫度(950 ℃以上)時, 單晶氧化物襯底上沉積的金剛石薄膜中的熱應(yīng)力σ達(dá)到–4~–8 GPa, 金剛石薄膜在生長至微米級厚度之后極易脫落[45]。

而由于金剛石與硅的熱膨脹系數(shù)較接近, 在Si上沉積的金剛石薄膜內(nèi)部的熱應(yīng)力相對較低(–0.68 GPa), 在較高沉積溫度下甚至更低[46], 例如在Si(100)/YSZ(100)/Ir(100)襯底上生長的金剛石薄膜, 其內(nèi)應(yīng)力33接近于0, 應(yīng)力矩陣如式(1)所示:

但硅與銥元素之間的化學(xué)反應(yīng)使得Ir薄膜不能直接沉積于Si襯底, 因此需要在Si襯底和Ir層之間沉積緩沖層。根據(jù)最底層襯底及緩沖層材料的不同, 可以形成不同的多層膜結(jié)構(gòu), 僅列出在Ir(100)晶面外延金剛石的生長質(zhì)量, 如表1所示。

其中, 生長質(zhì)量利用由X射線搖擺曲線半高寬得到的面內(nèi)傾斜角(tilt, Δ)和面外扭轉(zhuǎn)角(twist, Δrot)進(jìn)行表征。由表1可知, 在Ir(100)襯底上外延生長的金剛石薄膜均能達(dá)到極高的質(zhì)量。但以Si(100)作為襯底最底層時, 外延生長的單晶金剛石薄膜厚度可以達(dá)到較高的水平。與較小尺寸的氧化物單晶片相比, 尺寸大且熱膨脹系數(shù)與金剛石相近的Si單晶片為制備大尺寸自支撐金剛石晶片提供了技術(shù)可能。外延金剛石薄膜與各層襯底的取向關(guān)系為diamond(100) [100]||Ir(100)[100]||MO(100)[100] ||Si(100)[100][54]。

2 金剛石的形核過程

2.1 偏壓增強(qiáng)形核法與初級核的形成

襯底在微波等離子體化學(xué)氣相沉積(MPCVD)系統(tǒng)中共需經(jīng)歷H2清洗、甲烷穩(wěn)定化處理、形核和金剛石薄膜生長四個過程, 各步驟的參數(shù)如表2所示。對于形核過程, 一般來說, 形核密度越大, 金剛石的生長質(zhì)量越高, 最常用的增強(qiáng)形核方法為偏壓增強(qiáng)形核(Bias Enhanced Nucleation, BEN)法。在微波化學(xué)氣相沉積系統(tǒng)中, 既可以將負(fù)偏壓直接施加到襯底上, 也可以使襯底接地, 在等離子體球上施加正電壓[55-56]。

表1 基于Ir(100)襯底的不同膜系結(jié)構(gòu)上金剛石的外延質(zhì)量

表2 金剛石在Ir上形核及生長過程的實驗參數(shù)[59]

等離子體球在施加偏壓時會發(fā)生形變, 產(chǎn)生特殊的偏壓輝光區(qū), 如圖2所示, 該過程增大了等離子球與襯底的接觸面積, 同時加速了離子運動, 有利于金剛石的大面積形核, 同時可以提高形核密度和均勻性[58]。

BEN過程開始后, 銥襯底表面先形成非晶碳層(圖3(b1)), 偏壓為離子提供的能量使得含碳離子進(jìn)入Ir襯底的亞表面形成過飽和固溶體, 碳再從亞表面析出形成初級金剛石晶核(圖3(b2))[65]。由于Ir和金剛石具有相近的二次電子發(fā)射系數(shù), 金剛石在Ir上形核實際上是刻蝕金剛石大顆粒的過程[66]。由于該過程抑制了金剛石顆粒的生長, 可以持續(xù)進(jìn)行較長時間, 有利于金剛石大面積均勻形核[67], 形核密度可以達(dá)到3×1011cm–2[16]。但金剛石在Ir上形核的最佳偏壓和甲烷體積分?jǐn)?shù)的取值范圍較窄[68],在該范圍之外取值則會造成形核密度急劇下降[56]。

圖2 施加偏壓時等離子體球的形狀變化[57]

(a) Photograph; (b) Schematic

2.2 次級核的形成與襯底的表面形貌

初級核形成后, 會重整、規(guī)范其周圍碳原子排列結(jié)構(gòu)形成排列規(guī)則的金剛石晶核, 從而不斷擴(kuò)大形核區(qū), 形成次級核(圖3(b3))?？梢栽趻呙桦娮语@微鏡照片中觀測到該明亮區(qū)域[69], 這是形核過程的特征形貌, 也是之后金剛石晶核生長的區(qū)域[70]。原位觀測BEN過程及生長過程后的襯底, 可見外延的晶粒幾乎全部位于之前形成的明亮島狀區(qū)域內(nèi),這些區(qū)域外部幾乎沒有晶粒, 如圖4所示。可以利用這種現(xiàn)象, 在襯底上預(yù)先設(shè)置“形核區(qū)”, 從而達(dá)到選區(qū)外延效果, 這也屬于一種襯底圖形化的方法[71]。

停止施加偏壓并開始金剛石的生長過程5~10 s后, 在生長過程最初階段腔體內(nèi)甲烷濃度升高的情況下, 之前因離子撞擊穩(wěn)定沉積在襯底表面的無定型碳薄膜被快速刻蝕[45], 如圖3(b4)所示。

3 金剛石的生長過程

3.1 緩慢生長階段

金剛石生長過程可以分為緩慢生長和快速生長兩個階段, 生長過程參數(shù)見表2所示。緩慢生長過程即新金剛石晶核與形核階段金剛石晶核的連接與晶體尺寸增加過程。

圖3 單晶金剛石在銥(Ir)襯底上異質(zhì)外延的過程示意圖[16, 60-64]

(a) Preparation of substrate; (b) Bias Enhanced Nucleation (BEN) process; (c) Oriented growth; (d) Patterned growth; (e) Heteroepitaxial diamond

MS: Megnetron Sputtering; PLD: Pulsed Laser Deposition; MBE: Molecular Beam Epitaxy

圖4 利用二次電子探測器觀測到的SEM照片[72]

(a) BEN過程后銥襯底表面形貌; (b) BEN過程后銥襯底局部表面形貌; (c)生長過程后同一位置形貌

Fig. 4 SEM images[72]of the iridium surface after BEN treatment (a), local spots after BEN (b) and after a subsequent growth step (c)

比較常見的晶體材料的生長機(jī)制有奧斯特瓦爾德熟化(Ostwald Ripening, OR)[73]、定向附著生長(Oriented Attachment, OA)[74]和柯肯達(dá)爾效應(yīng)(Kirkendall Effect, KE)[75]等。定向附著生長是團(tuán)簇沿著特定的晶向聚集并最終形成單晶或?qū)\晶的過程, 具有非隨機(jī)性[76]。由于金剛石在Ir襯底上較高的形核密度, 金剛石生長的最初階段更傾向于OA生長機(jī)制, 可以認(rèn)為定向附著生長即為金剛石緩慢生長階段的微觀機(jī)理。

Li等[77]首次利用透射電子顯微鏡觀測到液體中晶粒的定向附著生長過程, 如圖5所示。Dong等[69]在外延薄膜中觀測到薄膜和過渡層晶粒的拓?fù)溲苌ㄏ蚋街L現(xiàn)象, 如圖3(c1)所示。Dideikin等[78]以爆轟法制備的納米金剛石為原料, 在高溫高壓條件下, 納米金剛石顆粒相接觸并發(fā)生傾斜、旋轉(zhuǎn), 每兩個顆粒的相同晶面通過懸掛鍵相連接, 最終形成1.5 μm的單晶金剛石顆粒, 從而驗證了固體顆粒之間的定向附著生長機(jī)制。但是對于金剛石在形核生長過程中的原位過程還缺少相應(yīng)的研究儀器和研究方法, 以至于金剛石的生長過程難以通過直觀的方法進(jìn)行觀測。

定向附著生長過程中, 晶界湮沒形成金剛石單晶是小角度晶界形成的楔形向錯所導(dǎo)致的。圖3(c2)為立方晶中的小角晶界及部分形成楔形向錯的結(jié)構(gòu)示意圖, 楔形向錯對應(yīng)于一個不完整的傾斜晶界[70]?？梢酝瞥鼍Я３叽绾途Ы甾D(zhuǎn)變?yōu)樾ㄐ蜗蝈e的臨界角crit之間的關(guān)系為[32]:

其中,為柱狀晶粒半徑, b為柏氏矢量。

還有一些研究者采用晶體相場法模擬異質(zhì)外延形核生長過程[79]和晶界湮沒過程[80], 將晶界看作若干刃型位錯, 并在生長或施加應(yīng)力、溫度場過程中不斷正負(fù)抵消, 最終晶界被完全移出晶體表面而消失, 從而形成單晶。

3.2 襯底圖形化生長方法

在晶體外延生長領(lǐng)域, 定向附著生長又可以稱為外延橫向生長(Epitaxial Lateral Overgrowth, ELO)[81]。根據(jù)ELO原理所延伸出的圖形化生長方法(Patterned Nucleation and Growth, PNG), 可以有效地減少Ir和金剛石界面處貫穿位錯的產(chǎn)生[82]。該過程的主要步驟為: 在已經(jīng)完成形核步驟的金剛石薄膜表面覆蓋點狀或條紋狀A(yù)u[83]、Ni[84]等材料的模板層(圖3(d1)), 利用等離子體刻蝕該表面(圖3(d2)), 或在金剛石形核后利用光刻將表面刻蝕成以Ir為生長模板、金剛石核為邊框的柵格網(wǎng)絡(luò)[85], 再繼續(xù)之后的生長過程[71](圖3(d3))。

另外, 可用HPHT法生長的金剛石作為襯底, Ir作為模板層[72, 86], 或者可在金剛石薄膜生長到一定厚度時, 將其刻蝕成納米針, 并在這些納米針表面完成金剛石薄膜的后生長[87-88], 甚至在該過程中直接使用HPHT單晶金剛石作為襯底, 進(jìn)行保護(hù)后刻蝕成納米針[84], 這些方法均可視作以Ir襯底上金剛石異質(zhì)外延為基礎(chǔ)的特殊的同質(zhì)外延方法。

利用襯底圖形化方法, 可有效地提高金剛石薄膜的生長質(zhì)量, 其面內(nèi)傾斜角的值可降低至0.064°, 面外扭轉(zhuǎn)角可低至0.043°[85], 與馬賽克法同質(zhì)外延生長的金剛石在非邊緣接縫處測得的數(shù)值在同一數(shù)量級(面內(nèi)傾斜角Δ= 0.012°)[89]。

3.3 快速生長階段

金剛石薄膜在快速生長過程開始后, 隨著厚度的增加, 其表面形貌、結(jié)構(gòu)和鑲嵌度都會有一定的改善, 貫穿位錯逐漸消失[90], 為異質(zhì)外延生長大尺寸單晶金剛石提供了可能性。圖6(a~c)為金剛石薄膜形貌的連續(xù)變化過程, 薄膜從由小顆粒組成最終生長成有缺陷的單晶。當(dāng)厚度為8 μm時, 直徑為 1 mm的單晶區(qū)域被由位錯組成的封閉的晶界網(wǎng)絡(luò)包圍, 厚度增加到34 μm時, 晶界網(wǎng)絡(luò)已經(jīng)分解成由位錯團(tuán)簇組成的較短位錯帶[48]。

圖6(d)利用(400)和(311)晶面X射線搖擺曲線半高寬表征面內(nèi)傾斜角(Δ)和面外扭轉(zhuǎn)角(Δrot), 從而說明在Ir襯底上外延金剛石薄膜的鑲嵌度隨金剛石薄膜厚度的變化。最初金剛石薄膜具有較大的面內(nèi)傾斜角和面外扭轉(zhuǎn)角, 在隨后的薄膜生長過程中, 傾斜角和扭轉(zhuǎn)角均隨薄膜厚度增加顯著降低, 該變化說明金剛石外延質(zhì)量得到了明顯提高[91]。也可利用Raman光譜檢測缺陷結(jié)構(gòu)的變化, 對于1 μm的薄膜, Raman峰半高寬>10 cm–1, 而對于厚度約為950 μm的薄膜, 半高寬值下降至1.86 cm–1, 接近于完美的金剛石單晶, 同時缺陷密度從>1010cm–2下降至<108cm–2[92]。這些研究均表明隨著金剛石薄膜厚度的增加, 其生長質(zhì)量有所提高, 這是異質(zhì)外延的一項顯著優(yōu)點。這就使得異質(zhì)外延生長的單晶金剛石可以在保證其良好質(zhì)量的同時, 達(dá)到較高的厚度水平, 為之后在各種器件中的復(fù)雜應(yīng)用提供了合適的材料基礎(chǔ)[91]。

由于最終生長的金剛石晶片中僅存在線缺陷, 而不再含有多晶材料中典型的連續(xù)晶界網(wǎng)絡(luò), 所以在Ir襯底上異質(zhì)外延的金剛石為單晶金剛石。這主要是由于形核和生長階段中以下的幾個影響因素所導(dǎo)致的: 首先, 形核過程所加偏壓對于金剛石大顆粒的刻蝕作用導(dǎo)致金剛石在Ir襯底上大面積、高密度均勻形核[66-67], 且由于Ir-C之間獨特的溶解–析出相互作用過程[35], 同時C原子在偏壓輔助形核過程中傾向溶解于Ir襯底亞表面形成過飽和固溶體[65], 均會導(dǎo)致C原子在亞表面和近表面區(qū)域有極高的運動速率, 為初級核的平移和旋轉(zhuǎn)提供驅(qū)動力, 從而易于形成與襯底相同的取向; 在次級核形成的過程中, C原子的快速移動也會導(dǎo)致規(guī)則排列的sp3結(jié)構(gòu)的晶核快速規(guī)整排列不夠整齊的結(jié)構(gòu), 最終形成統(tǒng)一的sp3結(jié)構(gòu)[16]; 另外晶粒表面由于附著大量的非飽和碳?xì)鋺覓戽I, 由前述過程所形成的次級核相互接觸形成的薄膜的鑲嵌度<1°, 晶粒之間易于通過定向附著生長的原理進(jìn)行連接[78], 以向錯代替晶界, 最終形成完整的單晶金剛石。

圖6 Ir/SrTiO3(100)上外延的不同厚度金剛石薄膜[48]

(a-c) TEM images; (d) Reduction in mosaic spreaded with increasing thickness

4 總結(jié)與展望

Ir襯底上異質(zhì)外延金剛石的研究已經(jīng)持續(xù)了30多年, 得到的單晶金剛石薄膜質(zhì)量在不斷提高, 尺寸也在不斷增大。本文對于在Ir襯底上異質(zhì)外延金剛石的過程進(jìn)行了描述和機(jī)理分析, 目前已有研究對單晶金剛石異質(zhì)外延襯底進(jìn)行了合理的設(shè)計和制備, 同時對單晶金剛石在Ir襯底上的形核、生長過程的各個階段進(jìn)行了理論上的解釋, 并提出了一些提高金剛石外延尺寸和質(zhì)量的方法。作為唯一一種技術(shù)上可實現(xiàn)的能夠制備大尺寸、高質(zhì)量單晶金剛石, 從而滿足其在各個領(lǐng)域應(yīng)用的方法, 金剛石的異質(zhì)外延得到了科學(xué)界的廣泛關(guān)注。但其在以下幾個研究方向上仍然存在一些值得深入研究的問題:

1) Ir襯底上金剛石異質(zhì)外延過程的原位實驗研究仍有待深入。目前對于金剛石異質(zhì)外延過程的實驗研究方法依然是以在一定生長時間后暫停實驗、取出試件并進(jìn)行觀測為主, 難以對整個過程進(jìn)行連續(xù)、完整的描述?，F(xiàn)有的原位透射電鏡和原位掃描電鏡等實驗儀器難以在金剛石生長條件下使用, 需要研究新的實驗和觀測方法。

2) 金剛石異質(zhì)外延生長過程中的n型摻雜。金剛石的n型摻雜一直是一項困難的工作, 但異質(zhì)外延單晶金剛石尺寸大、表面光滑、缺陷密度低, 為其在電子器件中的應(yīng)用提供了可能性, 基于異質(zhì)外延金剛石薄膜的n型摻雜是一項亟待研究的課題。

3) 金剛石異質(zhì)外延理論和全對稱材料的制備。目前, 關(guān)于在Ir襯底上的金剛石異質(zhì)外延研究主要集中在實驗層面, 理論研究上仍有較大的發(fā)展空間。比起晶格常數(shù)匹配度更佳的Ni、Cu等材料, Ir在金剛石異質(zhì)外延領(lǐng)域的出色表現(xiàn)質(zhì)疑了研究者之前認(rèn)為晶格常數(shù)匹配度是異質(zhì)外延的重要影響因素的假設(shè)。同時, 由于已經(jīng)實現(xiàn)在金剛石襯底上異質(zhì)外延Ir薄膜, 即已經(jīng)實現(xiàn)了金剛石、Ir的相互外延, 為制備全對稱材料提供了理論支持, 這對于異質(zhì)外延理論的發(fā)展具有重大意義。

為了使異質(zhì)外延金剛石能夠在相關(guān)領(lǐng)域展開應(yīng)用, 充分利用金剛石的優(yōu)異性質(zhì), 必須進(jìn)行大規(guī)模量產(chǎn)。目前, 異質(zhì)外延金剛石僅限于在實驗室中制備的樣品, 但想要應(yīng)用其優(yōu)良性能并制作成器件, 尚需對其制備工藝和技術(shù)進(jìn)行進(jìn)一步優(yōu)化和研究。

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Heteroepitaxial Growth of Single Crystal Diamond Films on Iridium: Procedure and Mechanism

WANG Yang, ZHU Jia-Qi, HU Zhong-Bo, DAI Bing

(Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080, China)

Due to its unique physical and chemical property, diamond is widely used in many fields such as detectors and optoelectronic devices. Many scholars’ attention is drew into single crystal diamond because of its potential to significantly increase the functionality of these devices. Presently, single crystal diamonds grown heteroepitaxially on iridium (Ir) substrates reach the largest size and an excellent growth quality. In this paper, substrates with different structures for nucleation and growth processes of epitaxial diamond are introduced. The mechanisms of diamond nucleation by Bias Enhanced Nucleation (BEN) method and growth undergoing an Epitaxial Lateral Overgrowth (ELO) process are described, including technique of Patterned Nucleation and Growth(PNG). Limitations of current study are pointed out, and the future development of heteroepitaxial theory and experiment are also forecasted in this paper.

single crystal diamond; heteroepitaxial growth; bias enhanced nucleation; epitaxial lateral overgrowth; review

O782

A

1000-324X(2019)09-0909-09

10.15541/jim20180587

2018-12-17;

2019-02-12

國家自然科學(xué)基金(51702066); 國家杰出青年科學(xué)基金(51625201); 國家重點研發(fā)計劃 (2016YFE0201600); 國家自然科學(xué)基金聯(lián)合基金重點項目(U1809210)

National Natural Science Foundation of China (51702066); National Science Fund for Distinguished Young Scholars (51625201); National Key Research and Development Program of China (2016YFE0201600); Key Project of National Natural Science Foundation of China (U1809210)

王楊(1991–), 女, 博士研究生. E-mail: ravimassa@163.com

朱嘉琦, 教授. E-mail: zhujq@hit.edu.cn