SI GaAS中S~+注入的电学特性

本文研究了经常规热退火和快速热退火后SIGaAs中S~+注入的电学特性.热退火后,GaAs中注入S~+的快扩散和再分布不决定于S~+或砷空位V_(AS)的扩散而决定于离子注入增强扩散.使用快速热退火方法能抑制注入S~+在GaAs中的增强扩散,明显减小S~+的再分布,可以获得适合于制造GaAs MESFET器件的薄有源层.     

Si,As双注入GaAs的RTA研究

本文研究了Si注入GaAs的快速退火(RTA)特性。得出930—950℃退火5s为最佳退火条件。测量结果表明,当注入剂量大于10~(13)cm~(-2)时,电子浓度呈饱和现象。为提高电子浓度本文提出Si,As双注入GaAs的方法,研究了(60—80)keV,(5—10)×10~(14)Si/cm~2+(150—180)keV,(5—30)×10~(14)As/cm~2注入并经RTA后的电特性。结果表明,双注入后样品中电子浓度有明显提高,对80keV,10~(15)Si/cm~2+150keV,3×10~(15)As/cm~2来说,电子浓度大于10~(19)cm~(-3)。TEM观察表明,双注入样品的剩余缺陷密度大大低于单注入的情况。本文并对双注入补偿机理进行了讨论。     

InP和GaAs中的Mg~+离子注入

本文研究了Mg~+离子注入InP和GaAs中的电学性能和辐射损伤行为.范德堡霍尔方法测量和电化学C-V测量均表明,快速热退火方法优于常规热退火方法,共P~+注入结合快速热退火方法能进一步减小注入Mg杂质的再分布,使电激活率大大提高。卢瑟福沟道分析则表明,相同注入条件下,InP中的辐射损伤较GaAs中大得多,大剂量注入损伤经热退火难于完全消除.     

黄昆X射线漫散射的实验研究

本文描述了黄昆X射线漫散射的实验方法及其所需的实验条件,并利用它研究了离子注入CaAs中点缺陷所引起的黄昆散射,在同一GaAs晶片上的不同部分分别注入Mo和Er,浓度均为1×10~(15)cm~(-2),注入电压为500keV,经850℃退火30分钟后分别在77K的条件下进行黄昆散射测量,实验观测到注入Er元素比Mo元素引起的黄昆散射要强,这一结果表明Er元素在GaAs中大多处于间隙状态,而Mo元素在GaAs中大多处于替换状态.     

Si,S,Be,Mg离子注入GaAs白光快速退火特性研究

利用灯光瞬态退火处理Si,S离子注入SI-GaAs样品,在950℃5秒的条件下得到了最佳的电特性,Be,Mg离子注入SI-GaAs样品在800℃ 5秒退火得到了最佳的电特性.Si,S,Be注入GaAs样品在适当的条件下得到了陡峭的载流子剖面分布,而Mg注入的样品有Mg的外扩散和较大的尾部扩散.透射电镜测量表明,Si低剂量和Be大剂量注入退火后单晶恢复良好,而Si和Mg大剂量注入退火后产生了大量的二次缺陷.应用Si和Mg注入GaAs分别制作了性能良好的MESFET和β=1000的GaAIAs/GaA,双极型晶体管(HBT).     

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.     

注Si~+的GaAs在GaAs粉末的砷气压下快速热退火

用卤素灯在砷气压下对注Si~+的GaAs进行快速热退火,以研究退火温度和退火时间对薄层载流子浓度和迁移率的影响。注入层的激活率主要受退火温度的影响,与退火的持续时间几乎无关。在800℃退火30分钟,GaAs的表面形态是平滑的,这表明了砷气压的存在防止了砷原子的蒸发,并使注入层能在高温下长时间退火而不会出现表面离解和电性能的下降。在GaAs中注入Si~+的激活能为0.53eV。     

半绝缘GaAs中Mg~++P~+双注入研究

本文对Mg~+和P~+双离子注入半绝缘GaAs的行为进行了研究.发现不论是常规热退火还是快速热退火,共P~+注入都能有效地提高注入Mg杂质的电激活率,其效果优于共As~+注入,共P~+注入的最佳条件是其剂量与Mg~+离子剂量相同,电化学C—V测量表明,双注入样品中空穴分布与理论计算值接近,而单注入样品中则发生严重偏离,快速热退火较常规热退火更有利于消除注入损伤.     

硅中硼离子注入层的卤钨灯辐照快速退火研究

本文研究了SiO_2掩蔽膜硼离子注入硅的卤钨灯辐照快速退火,测量了注入层表面薄层电阻与退火温度及退火时间的关系,得到了最佳的退火条件。对于采用920(?)SiO_2膜,25keV、1×10~(15)cm~(-2)的~(11)B离子注入样品,经不同时间卤钨灯辐照退火后,测量了注入层的载流子浓度分布,并与950℃、30分钟常规炉退火作了比较。结果表明,卤钨灯辐照快速退火具有电激活率高、注入杂质再分布小以及快速、实用等优点。     

直流磁控溅射TiN/GaAs肖特基结的电学特性研究

本文研究了经直流磁控溅射制备的TiN/GaAs肖特基结的电学特性.给出了不同退火温度下I-V,C-V测量结果及TiN/GaAs与Au/GaAs,Ti/GaAs,Al/GaAs接触特性的比较.应用AES与XPS进行肖特基结的表面和界面剖析,发现退火过程中TiN膜的氧化,N在TiN膜中的再分布及TiN-GaAs接触界面上的化学重组对肖特基结的接触特性有重要影响.     

Calculation of the optimum vapor pressure for stoichiometry in PbTe and PbSnTe

Optimum vapor pressure for stoichiometry in growth of PbTe and PbSnTe has been calculated. The result is in a good agreement with the experimentally obtained ones for vapor pressure controlled Bridgman growth and liquid phase epitaxy. The procedure of calculation follows that performed earlier for GaAs, which assumed the equality of the chemical potentials of the volatile element in gas, liquid and solid phases. Also it is pointed out that the nonequilibrium reactions of interstitial Te atoms with Pb vacancies forming anti-site Te, as well as Te precipitations, take place at the highest applied Te vapor pressure region.     

CdTe/GaAs(111)B薄膜的MBE生长研究

采用分子束外延方法,在GaAs(111)B衬底上,生长CdTe薄膜,以求研制出用于液相外延生长碲镉汞(HgCdTe)薄膜的CdTe/GaAs(111)B复合衬底.通过理论分析和实验探索,优化了生长温度和Te/Cd束流比等重要生长参数,获得了质量较好的CdTe薄膜,再通过循环热处理,使CdTe/GaAs(111)B复合衬底的质量得到进一步的提高,X-射线回摆曲线半峰宽(FWHM)有明显的降低.为LPE-HgCdTe薄膜的生长打下了较好基础.     

Tellurium implantation in GaAs

Electron concentration and mobility profiles for Te implanted semi-insulating GaAs samples annealed with a reactively sputtered silicon nitride protective layer (or cap) have been measured as a function of the dose of implanted Te and the annealing temperature. Results of high dose implants into n-type epitaxial samples are essentially the same as those obtained using semi-insulating material from different suppliers. Samples in which Ga was implanted either before or after the implantation of Te exhibited essentially the same electron concentration and mobility profiles as those in which only Te was implanted. Attempts to introduce As vacancies by preannealing Te implanted samples without a cap at temperatures between 550 and 700°C also had no effect on the measured profiles. The use of an aluminum oxy-nitride cap resulted in about twice the doping efficiency and three times the maximum electron concentration than was obtained with a silicon nitride cap for doses of 1 × 10¹⁴ Te ions/cm².     

Molecular beam epitaxy of CdTe and Hg1-xCdxTe ON GaAs (100)

Using the molecular beam epitaxial (MBE) technique, CdTe and Hg_1-xCd_xTe have been grown on Cr-doped GaAs (100) sub-strates. A single effusion cell charged with polycrystal-line CdTe is used for the growth of CdTe films. The CdTe films grown at 200 °C with a growth rate of ~ 2 μm/hr show both streaked and “Kikuchi” patterns, indicating single crystalline CdTe films are smoothly grown on the GaAs sub-strates. A sharp emission peak is observed at near band-edge (7865 Å, 1.577 eV) in the photoluminescence spectrum at 77 K. For the growth of Hg_1-xCd_xTe films, separate sources of HgTe, Cd and Te are used. Hg_0.6Cd_0.4Te films are grown at 50 °C with a growth rate of 1.7 μm/hr. The surfaces are mirror-smooth and the interfaces between the films and the substrates are very flat and smooth. As-grown Hg_0.6Cd_0.4Te films are p-type and converted into n-type by annealing in Hg pressure. Carrier concentration and Hall mobility of an annealed Hg_0.6Cd_0.4Te film are 1 × 10¹⁷ cm^?3 and 1000 cm²/V-sec at 77 K, respectively.     

利用AFM电场诱导GaAs表面的局域氧化制备纳米结构

基于ＡＦＭ电场诱导的方法成功地在掺杂ｎ型ＧａＡｓ（１００）和锌掺杂ｐ型ＧａＡｓ（１００）表面局域氧化制备了纳米尺度的点、线、图形,最小的纳米结构约１５ｎｍ,并定性地考察了ＧａＡｓ表面ＡＦＭ电场诱导制备的纳米结构的一些规律。     

Large area depositon of Cd1-xZnxTe on GaAs and Si substrates by metalorganic chemical vapor deposition

Results of large-area (up to 1000 cm²/run) Cd_1-xZn_xTe heteroepitaxy on both GaAs and GaAs/Si substrates by metalorganic chemical vapor deposition (MOCVD) are presented. Cd_1-xZn_xTe (x = 0-0.1) films exhibited specular surface morphology, 1% thickness uniformity (standard deviation), and compositional uniformity (Δx) of ±0.002 over 100 mm diam substrates. For selected substrate orientations and deposition conditions, the only planar defects exhibited by (lll)B Cd_1-xZn_xTe/GaAs/Si films were lamella twins parallel to the CdTe/GaAs interface; these do not propagate through either the Cd_1-xZn_xTe layer or subsequently deposited liquid phase epitaxy (LPE) HgCdTe layer(s). Background Ga and As-impurity levels for Cd_1-xZn_xTe on GaAs/Si substrates were below the secondary ion mass spectroscopy detection limit. Preliminary results of HgCdTe liquid phase epitaxy using a Te-rich melt on Si-based substrates resulted in x-ray rocking curve linewidths as narrow as 72 arc-sec and etch-pit densities in the range 1 to 3 x 10⁶ cm².     

Spontaneous formation of the periodic composition-modulated nanostructure in CdxHg1−x Te films

Anomalous electrical properties have been observed in Cd_xHg_1?x Te films grown on GaAs substrates by MBE at elevated temperature. The anomalies are manifested in the conductivity anisotropy, modifications of the transmission and photoconductivity spectra upon low-temperature annealing, and the existence of a periodic undulatory surface microprofile. The temperature dependence of conductivity along and across the microprofile waves has been studied. It is suggested that a Cd_xHg_1?x Te film with anomalous electrical properties is a spontaneously formed periodic structure in the form of vertical nanowalls of different compositions. Possible mechanisms for the formation of such a structure are discussed.     

Local Structure and Anti-Structural Defects of Tin in Amorphous and Crystalline Ge2Sb2Te5 Films

Semiconductors - The absorption Mössbauer spectroscopy on 119Sn impurity centers shows that germanium atoms in the structure of amorphous and polycrystalline Ge2Sb2Te5 films have different...     

Electrical characteristics of GaAs MIS Schottky diodes

The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of GaAs metal-insulator-semiconductor (MIS) Schottky barrier diodes are investigated over a wide temperature range and compared with MS diodes. The effects of the insulating layer on barrier height and carrier transport are delineated by an activation energy analysis. Excess currents observed at low forward and reverse bias have also been analyzed and their cause identified. A capacitance anomaly consistently noticed in MIS Schottky barriers is resolved by stipulating a non-uniform interfacial layer, and a self-consistent model of the GaAs MIS Schottky barrier is developed by analyzing I-V and C-V data of both MIS and MS diodes.     

A Roadmap for Controlled and Efficient n‐Type Doping of Self‐Assisted GaAs Nanowires Grown by Molecular Beam Epitaxy

N‐type doping of GaAs nanowires has proven to be difficult because the amphoteric character of silicon impurities is enhanced by the nanowire growth mechanism and growth conditions. The controllable growth of n‐type GaAs nanowires with carrier density as high as 10²⁰ electron cm^?3 by self‐assisted molecular beam epitaxy using Te donors is demonstrated here. Carrier density and electron mobility of highly doped nanowires are extracted through a combination of transport measurement and Kelvin probe force microscopy analysis in single‐wire field‐effect devices. Low‐temperature photoluminescence is used to characterize the Te‐doped nanowires over several orders of magnitude of the impurity concentration. The combined use of those techniques allows the precise definition of the growth conditions required for effective Te incorporation.