N-型ZnSe:Cl的分子束外延生长

本文报道利用分子束外延(MBE)技术,采用高纯ZnCl_2作掺杂源,成功地进行了n—型ZnSe:Cl的分子束外延生长。n-ZnSe:Cl/p-GaAs异质结构的伏-安(I—V)特性和热探针测试显示外延层呈n型导电特性。反射高能电子衍射(RHEED)和x射线衍散谱测量表明ZnSe:Cl外延层具有较好的晶体质量。     

MBE生长的InSb和InASxSb1—x的载流子浓度剖面分布

在(111)InSb 和(100)GaAs 衬底上,用分子束外延技术生长了 InSb 和 InAs_xSb_(1-x)外延层。用自动电化学 C—V 法测量了外延层的载流子浓度剖面分布。结果表明:(1)外延层呈 P 型;(2)InSb/GaAs 异质外延层的载流子浓度为(1～2)×10~(16)cm~(-3),比相应的同质外延层 InSb/InSb 的(1～2)×10~(17)cm~(-3)小一个数量级;(3)生长层的载流子浓度剖面分布和质量取决于衬底表面的制备。讨论了有关问题。     

优质GaAs/Si材料的研制

用国产分子束外延设备(Ⅳ型)在p型Si衬底上用三阶段生长法生长出优质GaAs外延层。测试样品为2μm厚,n型掺杂浓度5×10~(16)cm~(-3)。测量结果为x射线双晶衍射回摆曲线半峰宽225弧秒;低温光荧光谱半峰宽在10K时为5meV,外延层表面位错密度10~6cm~(-2)。     

用溅射淀积法外延生长优质Cd_xHg_(1-x)Te薄膜

采用汞蒸汽等离子体阴极溅射技术,已同时在几种CdTe衬底上(总面积为20cm~2)外延生长了Cd_xHg_(1-x)Te薄膜。薄膜在加热到310℃的衬底上生成,其淀积速率为0.6μm.h(总厚度≤30μm)。采用不同的实验方法对薄膜的结晶学特性进行了分析,这些方法包括:反射X-射线形貌、衍射分布图的半值宽度(FWHM)测量、透射电子显微镜分析(TEM)和卢瑟福反向散射分析(RBS)。TEM法,摆动曲线和RBS的结果揭示出薄膜具有很高的结晶学质量(外延层内的位错密度接近10~4cm~(-2))。在4K和300K之间测量了Cd_xHg_(1-x)Te外延层的霍耳系数。衬底温度为285℃时淀积的外延层(镉的组分为0.23,厚度16μm),在77K测量的结果是:载流子浓度n大约为2.7×10.(16)cm~(-3);霍耳迁移率为64000cm~2·V~(-1·S~(-1)。当镉的组分为0,31时(外延层厚度为18μm),则得到n=1.6×10~(16)cm~(-3);霍耳迁移率为16000cm~2·V~(-1)·S~(-1)。淀积出来的外延膜在双温区炉子内的汞气氛中退火后,其电学性质得到改善。n型外延膜的电子迁移率提高到接近用非最佳退火参量得到的体材料的水平。     

Ga_(1-x)Al_xAs-GaAs DH 激光器的质子轰击研究

质子轰击条形DH激光器,通常我们采用常规的液相外延方法来制造。一般在n-GaAs衬底材料上生长Ga_(1-x)Al_xAs-GaAs五层DH结构。n面衬底上的接触电极用AuGeNi合金化形成;p-GaAs顶层上则先扩散锌,蒸发Cr-Au。对质子束的掩蔽     

电化学光伏法测定n-和p-GaAs少子扩散长度

从GaAs/电解液界面的电化学研究,提出了一种适合于测定化合物半导体少子扩散长度的光电化学新方法──电化学光伏法,用它成功地测定了n-和p-GaAs体单晶及外延层的少子扩散长度。     

GaAs—Al_(0.3)Ga_(0.7)As DH结构中的界面复合

一、界面复合速度的测量: 1) 原理: 图1是GaAs-Al_(0.3)Ga_(0.7)As DH结构的示意图。注入到p-GaAs层内的少数载流子(电子)的寿命由体内复合和界面复合决定。令两组样品的p-GaAs层厚度为d_1和d_2,则可测出     

分子束外延中的掺硼工艺

我们在硅分子束外延中利用共蒸发B_2O_3的方法在硅中进行硼掺杂,掺杂浓度可控制在4×10~(17)cm~(-3)至4.2×10~(19)cm~(-3)之间,这说明不需要利用离子注入或高温掺杂炉,也可以在硅外延层中实现有效的P型硼掺杂.我们还对掺杂外延层的质量进行了初步分析:外延层剖面均匀、没有明显的偏析现象;当硅源速率在 2A/s时,外延层中氧含量与衬底相同.     

Cd_(0.2)Hg_(0.8)Te光电二极管表面漏电流的减少

在表面形成一层宽带隙外延层,可以减少Cd_(0.2)Hg_(0.8)Te光电二极管的表面漏电流。在CdTe衬底上,液相外延由p-Cd_xHg_(1-x)Te(x>0.2)/p-Cd_(0.2)Hg_(0.8)Te组成双层Cd Hg Te外延层。77K下,经范德堡霍尔测试,得到空穴载流子浓度和迁移率分别为9×10~(15)cm~(-3)和6×10~2cm~2V~(-1)s~(-1)。首先去除p-Cd_(0.2)Hg_(0.8)Te上面直径为100μm的宽带隙层,然后再向p-Cd_(0.2)Hg_(0.8)Te中扩铟而形成p-n结。77K下,有宽带隙层和无宽带隙层光电二极管的R_0A乘积分别为9.1Ωcm~2(λ_c=11μm)和2.0Ωcm~2(λ_c=10μm),这就证实了宽带隙层钝化层起到了减少表面漏电流的作用。     

半导体激光器

我们利用普通的液相外延(LPE)技术在n~+-GaAs衬底上制得均匀性良好的高质量四层外延片:第一层n-GaAlAs,厚25μm,载流子浓度为～1×10~(18)cm~(-3),第二层GaAs,有     

掺碳GaAs生长特性的研究

采用以碳纤维为碳源的固态源MBE技术，生长了不同厚度的重接碳GaAs以及具有不同表层厚度的δ碳掺杂GaAs，通过Nomarski干涉显微镜和原子力显微镜（AFM）对样品表面形貌的观察，分析了挨碳GaAs的生长过程和各种缺陷的产生，提出碳的掺入导致了GaAs材料的三维岛状生长，促进了各种缺陷的力生。提出了通过改善生长条件减少缺陷的途径。     

Sidegating effect of GaAs MESFETs in carbon doped GaAs substrate

The sidegating effect of GaAs MESFETs in carbon doped semi-insulating GaAs substrate was investigated. Measurement results suggest that both the hole injection at one part of the gate electrode, and the modulation of the width of the depletion layer near the interface between the channel and substrate, cause the sidegating effect of GaAs MESFETs. Also, with the increase of carbon concentration, the latter cause becomes dominant in the sidegating effect.<>     

碳掺杂GaAs激光器侧向扩展电流的研究

实验研究了碳掺杂ＧａＡｓ激光器帽层的侧向扩展电流对阈值的影响。     

大功率GaAs/GaAlAs单量子阱激光器

采用MOCVD技术在φ40mmGaAs衬底上研制成大功率GaAs/GaAlAs单量子阱激光器。该激光器激射波长为830～870nm,室温CW阈值电流密度小于350A/cm~2,最低值为310A/cm~2,输出光功率大于200mW/(单面,未镀膜)。     

In0．2Ga0．8As-GaAs复合应力缓冲层上的1.3μm InAs／GaAs自组织量子点

用光荧光谱和原子力显微镜测试技术系统研究了在2 nm In0.2Ga0.8As和x ML GaAs的复合应力缓冲层上生长的InAs/GaAs自组织量子点的发光特性和表面形貌.采用In0.2Ga0.8As与薄层GaAs复合的应力缓冲层,由于减少了晶格失配度致使量子点密度从约1.7×109 cm-2显著增加到约3.8×109cm-2.同时,复合层也有利于提高量子点中In的组份,使量子点的高宽比增加,促进量子点发光峰红移.对于x=10 ML的样品室温下基态发光峰达到1350 nm.     

GaN紫外探测器的Ti/Al接触的电学特性

在非故意掺杂的和掺Si的GaN薄膜上蒸镀Ti(24nm)/Al(nm)薄膜,氮气环境下400～800℃范围内进行退火。实验结果表明,在非故意掺杂的样品上,随退火温度的升高,肖特基势垒高度下降,理想因子升高,表面状况逐渐变差,600℃退火形成较低接触电阻的欧姆接触,比接触电阻率为3.03×10-4Ωcm2,而载流子浓度为5.88×1018cm-3的掺Si的样品未退火就形成欧姆接触,比接触电阻可达到4.03×10-4Ωcm2。     

Incorporation behaviour of carbon and silicon on (100) and (111) surfaces during growth of GaAs/GaAs and Ga0.47In0.53As/InP by molecular beam epitaxy

Silicon and carbontetrabromide were used as dopant sources in the growth of GaAs/GaAs and Ga_0.47In_0.53As/InP structures. We studied the incorporation behaviour of these group IV atoms on (100) and {111} surfaces as a function of growth temperature. The free carver concentrations determined by Hall measurements for Si-doped GaAs and Ga_0.47In_0.53As layers are independent of growth temperature on all surface orientations studied. Silicon acts fundamentally as a donor except, as expected, for doped layers on (111)A GaAs substrates, where it acts as an acceptor. Carbon incorporation in GaAs and Ga_0.47In_0.53As always results in a p-type conduction independent of the surface orientations (100)/{111} or the growth temperatures we used. In contrast to the results on GaAs, carbon shows a strong temperature-dependent activation in Ga_0.47In_0.53As grown on (100) and (111)B surfaces. Carbon-doped Ga_0.47In_0.53As on (111)A and carbon-doped GaAs layers on (100)/{111} GaAs surfaces exhibit only a very weak dependence of the carrier concentration on the growth temperature. A significant amphoteric behaviour of carbon was not observed in any of the materials investigated.     

Molecular beam epitaxial growth of carbon doped GaAs with elemental gallium and arsenic sources and a CCI4 gas source

CC1₄ has been used as a carbon acceptor dopant source for GaAs grown by elemental source molecular beam epitaxy. Deposition of CC1₄ during normal arsenic stabilized growth of GaAs resulted in low mobility, p-type material. Attempts to thermally crack the CC1₄ using a heated gas cracking source resulted in an even lower hole concentration and mobility. One possible explanation for this ineffective acceptor doping behavior, relative to growth environments containing hydrogen (metalorganic chemical vapor deposition) where CC1₄ is an effective dopant, is that hydrogen plays a role in the incorporation of the carbon. Another possible explanation for the poor doping behavior is that the CC1₄ was being modified by the gas cracker, even at relatively low gas cracker temperatures. Further experimentation with different injection schemes will be necessary to better understand the doping behavior. Depositing the CC1₄ onto static, gallium-rich surfaces produces GaAs:C with hole mobilities comparable to GaAs:Be. Average hole concentrations as high as 4 x 10¹⁹ have been demonstrated. Carbon doped AlGaAs/GaAs heterojunction bipolor transistors (HBT_s) have been fabricated with the same characteristics as Be doped HBTs grown in the same MBE system.     

掺钕、镱两种激活离子KGW晶体的喇曼光谱

文中对各喇曼振动模在不同方向入射和吸收的振动情况下进行了研究,从理论上分析了钨酸钾钆晶体的喇曼振动模式与各方向的差异。实验表明：不同入射方向和不同接收方向对拉曼光谱的影响较大,KGW晶体喇曼强度最大的模有190cm^-1、750cm^-1和885cm^-1三处。还对不同掺杂离子和不同掺杂浓度对拉曼谱的影响及其拉曼截面进行了一些分析。     

具有超高掺杂基区的GaAs赝HBT分析

超高掺杂GaAs具有明显的禁带变窄(BGN)效应,因此采用超高掺杂基区的GaAs同质晶体管也可获得HBT的效果.故称之为赝HBT(p—HBT)。本文根据实验结果讨论了超高掺杂情况下GaAs的BGN效应及其对有效本征载流子浓度的影响,并对np~+n型结构GaAs p—HBT的发射极注入效率和共发射极电流增益进行了理论分析。结果表明,当基区掺杂浓度高于1×10~(20)/cm~3时可以获得较好的器件特性。