氮离子注入对GaAs肖特基势垒性能影响的研究

本文利用离子注入方法,用不同剂量的氮离子对GaAs衬底进行注入实验。结果表明,氮注入明显地改善了Ti/n-GaAs肖特基势垒特性。     

ZrN/n-GaAs肖特基势垒特性研究

本文用RBS,AES和电特性测量等方法,研究了ZrN/n-GaAs肖特基势垒.结果表明ZrN/GaAs势垒有良好的电特性和高温稳定性.经850℃高温退火后,势垒高度为0.90eV,理想因子n=1.02.同时我们观察到,随着退火温度升高(从500℃升高到850℃),ZrN/GaAs势垒电特性有明显改进:肖特基势垒高度增大、二极管反向电流减小、二极管电容减小和反向击穿电压增大.以上特点表明,ZrN/GaAs是用于自对准高速GaAs集成电路的较为理想的栅材料.     

氮气氛下衬底负偏压预溅射对GaAs肖特基势垒性能的改善

本文研究了不同气氛下衬底负偏压预溅射对GaAs肖特基势垒特性的影响。我们发现,采用氮气氛下衬底负偏压预溅射新工艺能明显改善GaAs肖特基势垒特性:势垒高度增高,势垒电容减小和二极管反向击穿电压增大。这种新工艺对于GaAs肖特基势垒特性改善和GaAs MESFETs性能提高是一个非常有用的技术。     

自对准钨栅GaAs MESFET IC工艺

为了制备耐高温肖特基势垒,已采用RF或DC磁控溅射法在n~+n型GaAs衬底上溅射淀积钨(W)膜。这种膜具有良好的力学及电学性质。膜的可蚀性及肖特基势垒的热稳定性能够满足自对准栅IC的要求。新颖的自对准结构及用W栅制成的自对准离子注入GaAs MESFET初步特性能说明W栅工艺适用于GaAs IC。     

GaAs上反应溅射WN_x薄膜特性研究

本文用反应溅射方法,制备了WN_x薄膜,用X光衍射、俄歇能谱深度成分分析、表面电阻测量及电流—电压曲线,测量、研究了WN_x薄膜的性能及与GaAs的肖特基势垒特性.     

超薄外延CoSi2/n-Si的肖特基势垒接触特性

研究了超薄(～10nm)CoSi2/Si的肖特基势垒接触特性.Co(3-4nm)/Ti(1nm)双层金属通过快速热退火在Si(100)衬底上形成超薄CoSi2薄膜.X射线衍射测试表明该薄膜具有较好的外延特性.用I-V、C-V方法在82-332K温度范围内测试了CoSi2/Sj的肖特基势垒特性.用弹道电子发射显微术直接测量了微区肖特基势垒高度.测试表明,用Co/Ti/Si方法形成的超薄CoSj2/Sj接触在室温时具有优良的肖特基势垒特性,I-V方法测得的势垒高度为0.59eV,其理想因子为1.01;在低温时,I-V方法测得的势垒高度随温度降低而降低,理想因子则升高.采用肖特基势垒不均匀性理论,并假设势垒高度呈高斯分布,实验数据和理论吻合较好.     

TiN/n-GaAs肖特基势垒特性

本文用俄歇能谱(AES)、电流-电压(I-V)和电容-电压(C-V)电学测量等方法,研究了反应溅射制备的TiN/n-GaAs肖特基势垒特性.经800℃高温热退火后,TiN/n-GaAs势垒具有良好的整流特性和高温稳定性,其势垒高度为0.80cV,理想因子n为1.07.同时还观察到许多有意义的结果:即随着退火温度的升高(从500℃到800℃),TiN/n-GaAs肖特基二极管的势垒高度增大,势垒电容减小和二极管反向击穿电压增大.我们认为这可能与溅射过程中GaAs衬底中掺氮有关,并用Shannon模型(即金属/P-GaAs/n-GaAs结构)解释了以上结果.研究结果表明,在自对准GaAs MESFET工艺中,TiN是一种很有希望的栅材料.     

超薄外延CoSi_2/n-Si的肖特基势垒接触特性

研究了超薄(～10nm)CoSi2/Si的肖特基势垒接触特性.Co(3—4nm)/Ti(1nm)双层金属通过快速热退火在Si(100)衬底上形成超薄CoSi2薄膜.X射线衍射测试表明该薄膜具有较好的外延特性.用I-V、C-V方法在82—332K温度范围内测试了CoSi2/Si的肖特基势垒特性.用弹道电子发射显微术直接测量了微区肖特基势垒高度.测试表明,用Co/Ti/Si方法形成的超薄CoSi2/Si接触在室温时具有优良的肖特基势垒特性,I-V方法测得的势垒高度为0.59eV,其理想因子为1.01;在低温时,I-V方法测得的势垒高度随温度降低而降低,理想因子则升高.采用肖特基势垒不均匀性理论,并假设势垒高度呈高斯     

GaAs声表面波CCD延迟线

据Applied Physics Letters 1982年8月刊报道: 美国Illinois大学的M.J.Hoskins等利用GaAs良好的电声特性.实现了声表面CCD延迟线。该器件以多层GaAs结构中直接产生的声表面波(SAW)形成波势阱,该势阱穿过肖特基势垒形成的电子耗尽埋沟。通过二极管注入到埋沟内的电子在衬底表面陷入SAW势阱,与声波一起以声速移动。电荷穿过转移区之后,由一个反相偏置二极管检出。该器件由转区、输入和输     

影响WSi_x与GaAs接触特性的因素

自对准工艺可以降低GaAs FET的源漏电阻,提高跨导和截止频率.难熔金属硅化物WSi_x可用于自对准工艺.为得到较好的与GaAs接触的肖特基势垒特性和高温稳定性,本文较详细地实验研究了影响WSi_x与GaAs接触特性的诸因素,指出,除表面态外,主要有三种因素使WSi_x与GaAs之间的肖特基势垒二极管(SBD)性能变差:(1)Si在WSi_x中的含量;(2)界面情况——存在于GaAs表面的天然氧化层、退火后的互扩散和界面上生成的化合物;(3)溅射淀积WSi_x薄膜前,GaAs表面薄层的晶格状态.第三种因素对SBD性能的影响是在最近的实验中得到的.     

Application of the lamp-annealing method to the n+-layer of WSix-gate self-aligned GaAs MESFET's

The electrical properties of the Si-implanted n+-layer and the WSix/n-GaAs Schottky contacts were investigated after lamp annealing at temperatures up to 1050°C in order to apply the lamp-annealing method to the source-drain n+-layer of WSix-gate self-aligned GaAs MESFET's. Experimental results show that WSix/n-GaAs Schottky contacts are not subjected to interfacial degradation at temperatures required for fully activating the n+-implanted dopant. It is demonstrated that this method is effective in improving FET performance at short gate lengths of 1.0 µm. About a 50- percent improvement in K-value was achieved compared to conventional furnace-annealed FET's. It is implied that this improvement is due to reduced short-channel effects.     

Junction model and transport mechanism in hybrid PEDOT:PSS/n-GaAs solar cells

This study investigates the junction formation and interface properties of PEDOT:PSS/n-GaAs hybrid solar cells on planar GaAs substrates. Barrier height, photocurrent, dark saturation current and build-in potential at this hybrid interface are measured by varying n-GaAs doping concentrations. The work function and valence band edge of the polymer are extracted from ultraviolet photoelectron spectroscopy to construct the band diagram of the hybrid n-GaAs/PEDOT:PSS junction. The current-voltage characteristics were analyzed by using abrupt (p⁺n) junction and Schottky junction models. Contrary to the earlier results from the PEDOT:PSS/n-Si solar cells, the experimental evidence clearly suggested that the interface between n-GaAs and PEDOT:PSS more likely exhibited a Schottky type instead of a p⁺n junction. The current transport is governed by the thermionic emission of majority carriers over a barrier and not by diffusion. The dark saturation current density increases markedly owing to the increasing surface recombination rate in heavier n-doped GaAs substrates, leading to significant deterioration in solar cells performance.     

用于GaAs数字IC的难熔栅自对准技术研究

本文用直流磁控溅射方法在离子注入n型GaAs衬底上制备了WSi_xN_y难熔金属膜,研究了它的热稳定性、界面和势垒特性.同时对WSi_(0.6),W,WN等难熔栅金属膜也进行了研究.AES和SIMS分析表明,WSiN/GaAs的界面通过1000℃,10秒钟快速退火(RTA)或850℃,20分钟常规炉退火处理仍保持稳定,势垒高度达到0.8V,理想因子n=1.1.制作了WSiN栅自对准(SAG)增强和耗尽型MESFET.其跨导分别为154mS/mm和250mS/mm.用这一工艺制作的运放差分输入电路从直流到1千兆赫增益达29.5dB.     

A low-gate-leakage-current GaAs MESFET with a thin epitaxialsilicon layer

An n-channel depletion-mode GaAs MESFET with an Al gate and a 6-A epitaxial Si layer between the metal and the GaAs, grown in situ by molecular beam epitaxy, is described. Its DC electrical characteristics are compared with a similar control structure grown without the Si layer. The gate leakage current in the Al/Si/GaAs MESFETs was three to four orders of magnitude lower than in the control structure, due to all increased barrier height in the Al/Si/n-GaAs Schottky gate of 1.04 eV, versus 0.78 eV for the Al/n-GaAs structure. The differences in threshold voltages, I-V characteristics, and transconductances between the two devices are consistent with an enhanced effective barrier height for the Al/Si/GaAs MESFET     

Structural characterization of Ti and Pt thin films on GaAs(100) substrate

In an attempt to understand the Schottky barrier behavior of Ti/Pt/GaAs and Pt/Ti/ GaAs bimetal Schottky diodes, we have investigated the interfacial morphology of Ti and Pt thin films on GaAs(l00) substrate. The characterization was based on coverage profiling of Auger electron spectroscopy in conjunction with transmission electron microscopy. Emphasis was placed on film uniformity and atomic interdiffusion. The results showed Ga and As outdiffusion in Pt/GaAs interface and some oxygen incorporated in Ti film, but no evidence of clustering for both metal/GaAs systems.     

Determination of deep levels in semiconductors from C-V measurements

A method is presented that allows deep level density and energy of impurities in semiconductors to be routinely determined from simpleC-Vmeasurements of Schottky barriers. The method is particularly useful for material having levels with very long time constants that are not accessible by noise spectra measurements. The technique is illustrated by measurements of epitaxial n-GaAs which show a donor level at 0.83 eV below the conduction band.     

Electrical and chemical characterization ofW1-x-ySixNy (0⩽x⩽0.42,0⩽y⩽0.30) Schottky diodes for self-aligned gate GaAsMESFETs

WSiN Schottky diodes on GaAs have been electrically and chemically characterized for atomic silicon and nitrogen; compositions of 0 to 42% and 0 to 28%, respectively. It is found that the main cause for Schottky diode degradation, after high temperature annealing, is the out-diffusion of As from GaAs. For films with atomic nitrogen composition of ⩾5%, As outdiffusion is eliminated as long as the atomic Si composition is ⩽40%. WN films (5% nitrogen) were applied to the fabrication of self-aligned gate lightly doped drain MESFET's with buried P layer. A maximum transconductance, g_m, of 370 mS/mm, f_T of 33 GHz, and DCFL inverter delay of 29 ps are measured for a 0.5 μm gate technology     

Metal contacts to gallium arsenide

In this paper, some aspects that determine the properties of Schottky and ohmic contacts to GaAs are discussed. For Schottky barrier diodes (SBD), we present results of a comprehensive study involving 41 different metals. We pay special attention to Ru and show that its thermal and chemical stability makes it ideal for use in devices operating above room temperature and for experiments involving annealing. Further, we discuss the effect of different metallization methods on SBD properties and show that methods which use energetic particles, such as electron beam deposition and sputter deposition, often result in inferior SBD properties—the consequence of electrically active defects introduced by the energetic particles at and close to the semiconductor surface. The advantages of using Ru as contact material to GaAs are that it forms high quality, thermally stable Schottky contacts to n-GaAs and thermally stable ohmic contacts with low specific contact resistance to p-GaAs. The versatile applicability of Ru contacts makes them extremely important for future use in devices such as heterojunction bipolar transistors and solid state lasers.