Si/GaAs异质结界面态及其价带不连续性

本文报道用自洽EHT方法研究Si/GaAs异质结界面态分布和价带不连续性。用准共度晶格模型处理晶格失配问题,并对晶格常数作了修正。通过对Si/GaAs(111)、Si/GaAs(111)和Si/GaAs(110)异质结中Si应变和GaAs应变的情况,分别进行计算,得到界面态分布和价带不连续值等物理量,结果表明:它们不仅依赖于组成异质结的两种材料的体性质,而且还依赖于界面晶向和材料应变。文中给出了这些计算结果,并作了初步的讨论。     

GaAs/Si异质外延的新进展

本工作从原理和实验技术上证实了氯化物VPE技术可用于CaAs/Si异质外延.CaAs/Si外延层表面平整光亮.对外延层进行了组分测量、高分辨率电镜和X-射线衍射分析.结果表明,外延层是符合化学计量比的CaAs单晶,外延层浓度可控范围为10~(14)～10~(17)cm~(-3),纵向掺杂分布平坦.用这种材料制成MESFET样管,跨导为40mS/mm.     

用HREM研究MBE生长GaAs／Si异质结的微孪晶

由于可以把Si集成电路和GaAs光电子器件集成在一块电路上的广阔应用前景,而使人们对si上异质外延GaAs产生了浓厚的兴趣,但si和GaAs的晶格常数和热膨胀系数失配,GaAs/Si产生高的位错密度和微孪晶,由于这个原因,很难获得高质量的外延层及用这种材料生产优质的光电子器件,为了减少缺陷,研究缺陷的性质及其成因是很有意义的。已有很多人对GaAs/Si的微孪晶进行了研究,如吴小京等做出了微孪晶的结构模型,谢强华等观察到微孪晶的不对称分布,而对微孪晶的的形成机理还未见报     

Si/Co/GaAs体系中界面反应的竞争机制

本文采用AES、XRD和TEM等技术对Si/Co/GaAs三层结构的界面反应作了较详细的研究。结果表明:Si/Co与Co/GaAs两界面的反应具有一定的相似性,即当退火温度低于300℃时,两界面都保持完整;当退火温度高于400℃时,两界面都发生了化学反应,并形成相应的化合相。由于两界面的初始反应条件相近,因而界面反应存在着竞争机制,通过进一步的实验,结果表明;Si/Co界面的反应速度要比Co/GaAs的快,从而为在GaAs衬底上形成CoSi_2/GaAs金半接触提供了有利条件。     

GaAs/Si/AlAs异质结的DLTS实验研究

利用深能级瞬态谱(DLTS)技术研究了Si夹层和GaAs层不同生长温度对GaAs/AlAs异质结晶体品质的影响.发现Si夹层的引入并没有引起明显深能级缺陷,而不同温度下生长的GaAs/Si/AlAs异质结随着温度的降低,深能级缺陷明显增加,并进行了分析,得到深能级是由Ga空位引起的,在600℃时生长的晶体质量最佳.     

SiGe/SiHBT异质界面与pn结界面的相对位移的影响

从模拟和实验两方面研究了SiGe/Si HBT发射结中pn结界面和SiGe/Si界面的相对位置对器件的电流增益和频率特性的影响.发现两界面偏离时器件性能会变差.尤其是当pn结位于SiGe/Si界面之前仅几十?就足以产生相当高的电子寄生势垒,严重恶化器件的性能.据此分析了基区B杂质的偏析和外扩对器件的影响以及SiGe/Si隔离层的作用.     

AlGaAs/GaAs Heterojunction Bipolar Transistors on Si substrateusing epitaxial lift-off

Epitaxial lift-off (ELO) technique was used for the first time to transplant AlGaAs/GaAs Heterojunction Bipolar Transistors (HBT's) to Si substrates. Both preprocessed (devices processed before transplantation) and postprocessed (devices processed after transplantation) ELO HBT's on Si were demonstrated in this study. The characteristics of those HBT's on Si with either technique show nearly identical characteristics of the HBT's on GaAs without transplantation, indicating the film quality is maintained after transplantation. Devices with a high current gain of 550 were transplanted without any degradation, and the current gain is not limited by the ELO process. This current gain value is the highest reported for GaAs HBT's on Si with any techniques     

异质结界面电子输运性质

本文概述了异质结界面电子输运性质的理论分析和实验研究.这些基本特性的研究将为微波和高速逻辑应用所需的材料及器件研制开辟新途径.     

InGaAsP/InP异质结界面态的变频C-V研究

本文利用自建的变频C-V测试系统测量分析了InGaAsP/InP异质结的界面态,结出其界面态密度和时间常数.实验结果表明,在界面同时存在快、慢界面态,其参数分别为快界面态:N_(s1)=7.3×10~(11)eV~(-1)·cm~(-2),τ_1=2.2×10~(-5)s慢界面态:N_(s2)=2.5×10~12eV~(-1)·cm~(-2),τ_Q=1.5×10~(-2)s     

Si／Si1—xGex异质结器件

本文综述了国外Si/Si_(1-x)Ge_xHBT的发展状况,把出Si_(1-x)Ge_xHBT的特点和优越性,分析了Si_(1-x)Ge_xHBT的制造技术和设备要求,指出了Si/Si_(1-x)Gex器件的应用前景。     

氢化非晶碳膜与硅的界面特性

利用直流辉光放电分解碳氢气体来淀积ａ－Ｃ：Ｈ膜，通过测量Ａｌ／ａ－Ｃ：Ｈ／ＳｉＭＩＳ结构的高频Ｃ－Ｖ曲线讨论了ａ－Ｃ：Ｈ／Ｓｉ界面的电子特性，结果表明ａ－Ｃ：Ｈ／Ｓｉ膜有可能用作半导体器件的表面钝化膜。     

Properties of a poly-Si/GaAs layered structure on Si for Si heterojunction bipolar transistor

The properties of poly-Si/GaAs layered films on Si for use in wide bandgap emitters for Si heterojunction bipolar transistors (Si-HBTs), were studied. A smooth GaAs film surface grown on Si was obtained at low temperature (200° C) from the initial stage of growth. The x-ray diffraction (XRD) results indicated that strong GaAs orientation (111) was obtained for the poly-Si/GaAs/Si-substrate layered structure after annealing at 800° C for 20 sec. Secondary ion mass spectroscopy (SIMS) profiles indicated that impurity diffusion from the GaAs layer into the p-type Si substrate was negligible at 800° C. The electrical characteristics forn-poly-Si/n-GaAs/p-Si-substrate heterojunction diodes were also investigated.     

Fabrication of GaAs/Si Heterostructures and Their Photoelectric Properties

Fabrication of GaAs/Si heterostructures and their photoelectric properties are investigated by Raman, photoluminescence and Hall-effect measurements. The crystallinity of GaAs epilayers grown on Si substrate is significantly affected by the substrate orientation and the growth method. The photoelectric properties of GaAs epilayers grown on Si （211） substrates deposited by using a two-step growth method are improved. These results indicate that GaAs epilayersgrownonSi （100） andSi （211） substrates by using two step growth method are promising for potential applications in high-speed and high-frequency photoelectric devices.     

Influences of Low Energy Ion Implantation on Properties of Polyaniline／Si Heterojunction Solar Cells

Ion implantation may favorably modify the properties of polyaniline/Si heterojunction solar cells fabricated by the electrochemical method. Influences of the implantation on the absorption spectrum and the thermal stability were discussed and output properties were measured. The results show that the absorption spectrum of the polyaniline films modified by ion implantation is much wider; its pyrolytic temperature increases by 40 ℃, and the polyaniline/Si cell efficiency increases 18 and 3 times under the illumination of 10.92 and 37.2 W/m^2 , respectively.     

AlGaAs/GaAs Heterojunction bipolar power transistors

An AlGaAs/GaAs heterojunction bipolar transistor with a total emitter periphery of 320 ?m has been developed for power amplifier applications. For the base contact, Zn diffusion was used to convert the n-type emitter material into p-type with a doping of ?1.0 × 1020 cm?3. Because of the highly doped layer, contact resistivity was extremely low (5 × 10?7 ?cm2). At 3 GHz, a CW output power of 320 mW with 7 dB gain and 30% power-added efficiency was obtained. Under pulsed operation, the output power increased to 500 mW with 6 dB gain and 40% power-added efficiency. With further device structure optimisations, the power performance of heterojunction bipolar transistors is expected to rival, or even surpass, that of the GaAs MESFETs.