AlN 和 SiO_xN_y 薄膜与其 GaAs 衬底间界面应力的喇曼光谱研究

本文用喇曼散射方法研究了在ＧａＡｓ衬底上用Ｓ－枪磁控反应溅射的ＡｌＮ和ＰＥＣＶＤ淀积的ＳｉＯｘＮｙ薄膜的界面应力，并研究了这两种薄膜在Ｎ２和Ａｒ气氛下的高温热处理对界面应力的影响．结果表明，与ＳｉＯｘＮｙ薄膜不同，在ＧａＡｓ衬底上制备的ＡｌＮ薄膜，其界面应力很小，而且经Ｎ２和Ａｒ气氛下的高温快速热退火，仍具有较好的稳定性，从而表明ＡｌＮ是ＧａＡｓ集成电路技术中一种较好的绝缘介质、钝化层和保护材料．     

AIN和SiOxNy薄膜与其GaAs衬底间界面应力的喇曼光谱研究

本文用喇曼放射方法研究了在ＧａＡｓ衬底上用Ｓ－枪磁控反应溅射的ＡＩＮ和ＰＥＣＶＤ淀积的ＳｉＯｘＮｙ薄膜界面应力，并研究了这两种薄膜在Ｎ２和Ａｒ气氛下的高温热处理对界面应力的影响。结果表明，与ＳｉＯｘＮｙ薄膜不同，在ＧａＡｓ衬底上制备的ＡＩＮ薄膜，其界面应力很不，而且经Ｎ２和Ａｒ气氛下的高温快速热退火，仍具有较好的稳定性，从而表明ＡＩＮ是ＧａＡｓ集成电路技术中一种较好的绝缘介质、钝化层和保护材料。     

Cr/GaAs(100)界面形成和界面反应的SRPES研究

利用同步辐射光电发射研究了Ｃｒ／ＧａＡｓ（１００）界面形成和结构．室温下，当Ｃｒ覆盖度低于０．２ｎｍ时，Ｃｒ与ＧａＡｓ衬底的作用很弱，没有反应产物生成．覆盖度高于０．２ｎｍ时，开始发生界面扩散和反应，Ａｓ原子与Ｃｒ生成稳定的ＣｒＡｓ化合物，而Ｇａ原子则与Ｃｒ形成组分变化的ＣｒＧａ合金相，并居于界面处．提高界面形成温度可显著地加剧界面混合和反应，引起表面偏析Ａｓ的出现．芯能级谱的结合能与强度分析表明，反应产物可作为有效的势垒（化学陷阱），阻止衬底的Ｇａ的外扩散．此外还比较了Ｃｒ与ＧａＡｓ（１００）及ＧａＡｓ     

CoSi_2可望成为GaAs MESFET自对准工艺中的栅极材料

本文选用了Ｃｏ／Ｓｉ／ＧａＡｓ结构作为研究对象，经６００℃恒温退火及８００℃快速退火处理后，分别在ＧａＡｓ衬底上形成Ｃｏｓｉ２／ＧａＡｓＳｃｈｏｔｔｋｙ接触．采用多种薄膜和界面的测试技术，对ＣｏＳｉ２：／ＧａＡｓ的薄膜及界面特性进行了细致的研究．结果表明：热退大处理后，Ｃｏ／Ｓｉ经化学反应形成了较均匀的ＣｏＳｉ２单相，其薄膜电阻率约为３０μΩｃｍ．即使经９００℃的快速返火处理后，ＧａＡｓ界面仍保持相当的完整性，同时薄膜形貌也很理想．此外，采用Ｉ－Ｖ电学测试法对经７５０℃恒温退火处理后形成的ＣｏＳｉ２／Ｇａ     

S钝化GaAs(100)衬底上分子束外延ZnSe薄膜的喇曼光谱研究

用分子束外延法（ＭＢＥ）分别在经（ＮＨ４）２Ｓｘ溶液和Ｓ２Ｃｌ２溶液钝化的ＧａＡｓ（１００）衬底上生长了ＺｎＳｅ薄膜．用室温喇曼光谱对不同处理方法的ＧａＡｓ上所长ＺｎＳｅ薄膜的晶体质量和ＺｎＳｅ／ＧａＡｓ界面进行对比研究．用喇曼散射的空间相关模型定量分析了一级喇曼散射的空间相关长度与晶体质量间的关系．根据ＧａＡｓ的ＬＯ－等离子激元耦合模喇曼散射强度的变化，分析了不同Ｓ钝化方法对ＺｎＳｅ／ＧａＡｓ界面以及ＺｎＳｅ薄膜质量的影响．结果表明，Ｓ２Ｃｌ２溶液钝化的ＺｎＳｅ／ＧａＡｓ样品具有较低的界面态密度和较好的     

利用CBE技术在Si衬底上生长GaAs薄膜

采用化学束外延（ＣＢＥ）技术，以三乙基镓（ＴＥＧ）和砷烷（ＡｓＨ３）为源，在Ｓｉ（００１）衬底上生长ＧａＡｓ薄膜．利用Ｈａｌｌ效应、卢瑟福背散射（ＲＢＳ）和高分辨率透射电子显微镜（ＨＲＴＥＭ）检测了外延层的质量．结果表明，ＧａＡｓ薄膜具有ｎ型导电性，载流子浓度为１．３×１０１５ｃｍ－３，其杂质估计是Ｓｉ，它来自衬底的自扩散．外延层的质量随着膜厚的增加而得到明显的改善．在ＧａＡｓ／Ｓｉ界面及其附近，存在高密度的结构缺陷，包括失配位错、堆垛层错和孪晶．这些缺陷完全缓解了ＧａＡｓ外延层和Ｓｉ衬底之间因晶格失配引     

AlN/GaAs界面的AES和XPS研究

在室温下用直流磁控反应溅射的方法制备了ＡｌＮ薄膜．用ＡＥＳ方法和ＸＰＳ方法分析了ＡｌＮ膜和ＡｌＮ／ＧａＡｓ界面．在ＡｌＮ／ＧａＡｓ界面发现了Ｏ—Ａｌ键,没有发现Ｏ—Ｇａ键或Ｏ—Ａｓ键．本文通过实验证明,ＡｌＮ／ＧａＡｓ界面的Ｏ元素在ＡｌＮ淀积过程中从ＧａＡｓ表面转移到ＡｌＮ膜中．这与通过ＰＥＣＶＤ方法淀积ＡｌＮ薄膜形成的ＡｌＮ／ＧａＡｓ界面完全不同．由于ＡｌＮ／ＧａＡｓ界面的Ｏ元素是与Ａｌ结合的,因此有较好的界面特性．这是直流磁控反应溅射方法制备的ＡｌＮ薄膜适用于ＧａＡｓ器件钝化的主要原因     

直流磁控溅射制备用于G aA s M E SFET钝化的AlN的工艺研究

室温下,用直流磁控反应溅射方法在Ｎ２／Ａｒ混合气体中淀积了ＡｌＮ薄膜,所用衬底是（１００）面的半绝缘ＧａＡｓ单晶片．研究了反应条件,如反应气压、反应气体配比、直流功率,对薄膜的物理性质和化学性质的影响．为了得到适于ＧａＡｓＭＥＳＦＥＴ钝化的薄膜,还对反应条件进行了优化．     

MBE生长InAs薄膜输运性质的研究

在ＧａＡｓ衬底上ＭＢＥ生长大失配ＩｎＡｓ薄膜，虽然在界面处存在大量位错，但仍能在ＩｎＡｓ薄膜中得到较高的电子迁移率．掺Ｓｉ样品的迁移率比同厚度未掺杂的样品要高．且对未掺杂的ＩｎＡｓ薄膜，迁移率在室温附近有一个明显的极小值．这些反常行为可以通过体层和界面层电子的并联电导模型来解释．     

分子束外延CdTe（211）B／GaAs（211）B的特性研究

ＣｄＴｅ／ＧａＡｓ是ＨｇＣｄＴｅ分子束外延的重要替代衬底材料。用Ｘ双晶衍射和光致发光测试研究了分子束外延生长的ＣｄＴｅ（２１１）Ｂ／ＧａＡｓ（２１１）Ｂ的晶体结构质量，表明外延膜晶体结构完整，具有很高的质量。用高分辨率的透射电镜研究其界面特性，观察到ＣｄＴｅ（２１１）Ｂ相对于ＧａＡｓ（２１１）Ｂ向着［１１１］方向倾斜一个小角度（约３°），界面的四面体键网发生扭曲，由于晶格失配，在界面存在很高的失配位错密度。用二次离子质谱分析仪分析了ＧａＡｓ衬底中的Ｇａ和Ａｓ向ＣｄＴｅ外扩散的情况。结果表明：如果要在ＧａＡｓ衬底上生长ＨｇＣｄＴｅ外延膜，必须先生长一层具有一定厚度的ＣｄＴｅ来阻止Ｇａ和Ａｓ向ＨｇＣｄＴｅ的外扩散和失配位错的延伸。     

GaN外延材料测试技术的研究

分别用金属In和Ti/Al/Ni/Au合金层制备GaN HEMT结构外延片的霍尔测试电极,并对样品进行霍尔测试.发现In金属与外延片形成非欧姆接触,Ti/Al/Ni/Au合金层与外延片形成良好的欧姆接触.用电化学C-V方法测试样品,得到的载流子浓度与合金电极制备的样品经霍尔测试得到的载流子浓度一致,从而验证了此种霍尔测试方法的准确性,为GaN外延材料的测试提出了准确可行的测试方法.     

Performances of novel Pd/Sn and Pd/Sn/Au ohmic metallizations to n-GaAs

Performance of novel Pd/Sn and Pd/Sn/Au Ohmic metallizations to n-GaAs have been investigated. Metallizations were deposited using a resistance heating evaporator and annealings were performed utilizing a conventional graphite strip annealer (cGSA). Metallization samples were characterized using scanning tunneling microscopy (STM), secondary ion mass spectrometry (SIMS) and current–voltage (I–V) measurements. Contact resistivities, ρ_c, of the metallizations were measured utilizing conventional transmission line model (cTLM) method. Novel Pd/Sn and Pd/Sn/Au Ohmic contacts exhibit better thermal stability compared to non-alloyed Pd/Ge metallization. In order to investigate the effectiveness of novel Pd/Sn and Pd/Sn/Au Ohmic metallizations in device applications, gallium arsenide metal-semiconductor field-effect transistors (GaAs MESFETs) have been fabricated. MESFETs fabricated with Pd/Sn/Au Ohmic contacts show a extrinsic transconductance, g_me, of more than 133 mS/mm for a gate length, L_G, of 2 μm.     

DC/DC辐照损伤与VDMOS器件1/f噪声相关性研究

通过对DC/DC转换器低频噪声测试技术以及在γ辐照前后电性能与1/f噪声特性变化的对比分析,发现使用低频噪声表征DC/DC转换器的可靠性是对传统电参数表征方法的一种有效补充.对DC/DC转换器辐照损伤与其内部VDMOS器件1/f噪声相关性进行了研究,讨论了引起DC/DC转换器辐照失效的原因.     

Low-temperature degradation studies of AlGaAs/GaAs modulation-doped field effect transistors

The degradation of AlGaAs/GaAs modulation-doped field effect transistors (MODFETs) was studied at the low temperature of 77 K. The MODFETs were stress tested at 77 K under both short- and long-term bias stress conditions. The measured MODFET parameters include threshold voltage V_t, transconductance g_m and the gate voltage V_u at which g_m shows a maximum. Shifts of V_t, g_m and V_u were studied as a function of stress voltage and stress time. The measured shifts are found to depend on (V_g − V_d) which indicates the influence of hot electrons coming from the high mobility channel. The MODFETs were also tested for temperature cycling between 300 and 77 K up to 20 cycles. Some changes of device properties at 77 K were observed.     

Proton-exchanged LiNbO/sub 3/ optical waveguides using stearic acid

Proton-exchanged optical waveguides have been fabricated in z-cut LiNbO/sub 3/ using a new proton source: stearic acid. These waveguides were characterized optically and were found to exhibit a step index profile with Delta n=0.118 measured at 0.633 mu m. The propagation losses were typically around 1.5 dB/cm, and the diffusion constant and the activation energy for the proton-exchange process were measured to be 5*10/sup 6/ mu m/sup 2//h and 69 kJ/mol, respectively.<>     

Metal-ferroelectric-insulator-semiconductor memory FET with long retention and high endurance

A ferroelectric memory field-effect transistor (FET) with a Pt-SrBi/sub 2/Ta/sub 2/O/sub 9/-Hf-Al-O-Si gate stack was fabricated and its electrical properties were characterized. The insulating and ferroelectric layers were successively deposited by a laser ablation technique. Excellent data retention characteristics were obtained. The drain currents of on- and off-states were measured as a function of time, after /spl plusmn/6 V poling voltage applied to the gate electrode. The current ratio of the on- and off-states was more than 10/sup 6/ even after 12 days. Moreover, after 10/sup 12/ cycles of /spl plusmn/8 V pulses, this ratio was also more than 10/sup 6/.     

Ga0.51In0.49P/In0.15Ga0.85As/GaAs pseudomorphic doped-channel FET with high-current densityand high-breakdown voltage

Ga_0.51In_0.49P/In_0.15Ga_0.85 As/GaAs pseudomorphic doped-channel FETs exhibiting excellent DC and microwave characteristics were successfully fabricated. A high peak transconductance of 350 mS/mm, a high gate-drain breakdown voltage of 31 V and a high maximum current density (575 mA/mm) were achieved. These results demonstrate that high transconductance and high breakdown voltage could be attained by using In_0.15Ga_0.85As and Ga_0.51In_0.49P as the channel and insulator materials, respectively. We also measured a high-current gain cut-off frequency f_t of 23.3 GHz and a high maximum oscillation frequency f_max of 50.8 GHz for a 1-μm gate length device at 300 K. RF values where higher than those of other works of InGaAs channel pseudomorphic doped-channel FETs (DCFETs), high electron mobility transistors (HEMTs), and heterostructure FETs (HFETs) with the same gate length and were mainly attributed to higher transconductance due to higher mobility, while the DC values were comparable with the other works. The above results suggested that Ga_0.51In_0.49P/In_0.15Ga_0.85 As/GaAs doped channel FET's were were very suitable for microwave high power device application     

Effect of annealing on GaN-insulator interfaces characterized by metal-insulator-semiconductor capacitors

GaN metal-oxide-semiconductor (MOS) capacitors have been used to characterize the effect of annealing temperature and ambient on GaN-insulator interface properties. Silicon dioxide was deposited on n-type GaN at 900 /spl deg/C by low-pressure chemical vapor deposition and MOS capacitors were fabricated. The MOS capacitors were used to characterize the GaN-SiO/sub 2/ interface with a low interface-state density of 3 /spl times/ 10/sup 11/ cm/sup -2/eV/sup -1/ at 0.25 eV below the conduction band edge, even after annealing in N/sub 2/ at temperatures up to 1100 /spl deg/C; however, insulator properties were degraded by annealing in NO and NH/sub 3/ at 1100 /spl deg/C.     

Modeling of boron and phosphorus implantation into (100) Germanium

Boron and phosphorus implants into germanium and silicon with energies from 20 to 320 keV and ion doses from 5/spl times/10/sup 13/ to 5/spl times/10/sup 16/ cm/sup -2/ were characterized using secondary ion mass spectrometry. The first four moments of all implants were calculated from the experimental data. Both the phosphorus and boron implants were found to be shallower in the germanium than in the silicon for the same implant parameters and high hole concentrations, as high as 2/spl times/10/sup 20/ cm/sup -3/, were detected by spreading resistance profiling immediately after boron implants without subsequent annealing. Channeling experiments using nuclear reaction analysis also indicated high substitutional fractions (/spl sim/19%) even in the highest dose case immediately after implant. A greater straggle (second moment) is, however, observed in the boron implants in the germanium than in the silicon despite having a shorter projected range in the germanium. Implant profiles predicted by Monte Carlo simulations and Lindhard-Scharff-Schiott theory were calculated to help clarify the implant behavior. Finally, the experimentally obtained moments were used to calculate Pearson distribution fits to the boron and phosphorus implants for rapid simulation of nonamorphizing doses over the entire energy range examined.     

Noise suppression characteristics of InP-based monolithically integrated guided wave balanced photodiodes

Measurements were made of the noise suppression and signal enhancement properties of dual In/sub 0.53/Ga/sub 0.47/As-InP metal-semiconductor-metal (MSM) photodiodes integrated with a leaky mode In/sub 0.52/Al/sub 0.48/As waveguide directional coupler, and an electro-optic phase shifter. The experiments were done with a 1.3- mu m laser as the local oscillator. A noise suppression of 11 dB and signal enhancement of 1.3 dB were recorded for the MSM photodiodes.<>