(NH4)2S硫化后ZnS/InP界面的电学特性

在(NH4)2S硫化后的n-型InP衬底上热蒸发ZnS薄膜制得Au/ZnS/InP(100)MIS器件，测得了其I-V特性曲线以及3MHz下的高频C-V曲线和100Hz下的准静态C-V曲线从这些曲线得到如下结果：正向饱和电流为7e-13A; ZnS钝化下经硫化的n-型InP表面的固定电荷密度为-2.28e11/cm2；禁带中的最低表面态密度约为1e12cm-2·eV-1. 上述结果表明经硫化后的ZnS/InP界面具有良好的界面特性.     

表面硫钝化对GaAs材料光响应特性的影响

采用湿法硫钝化的方式,显著降低了砷化镓(GaAs)材料的表面态密度。钝化处理后的GaAs薄膜光致发光强度提高了约14倍,光电流和响应度均增大。从能带角度分析了样品性能提升的原因,结果表明,钝化处理有利于表面态密度和肖特基势垒高度的调节,进而提升了样品性能。     

（NH4）2S硫化处理后InGaAs表面特性的研究

通过（NH4）2S湿法硫化InGaAs表面，利用微波反射光电导衰减法测量了经（NH4）2S硫化后的少数载流子寿命。结果显示，经过硫化处理后的InGaAs表面复合速度接近于理想的InP／InGaAs双异质结材料的界面复合速度。为了更好地表征钝化效果，在硫化后的InGaAs表面淀积SiNx制备了MIS结构，通过高低频C—V测试得出两者的界面态密度为8．5×10^10cm^-2·eV^-1。     

调制掺杂AlxGa1-xN/GaN异质结中AlxGa1-xN势垒层表面态及其他局域态性质研究

通过测量调制掺杂Al0.22Ga0.78N/GaN异质结样品的变频电容-电压(C-V)特性,对Al0.22Ga0.78N势垒层表面态的性质进行了研究.结果发现在小偏压下,样品的电容随着测量信号频率的增加而下降,说明势垒层中存在表面态.实验数据分析表明:表面态密度约为1013cm-2量级,表面态的时间常数比势垒层中其他局域态大.随着空间隔离层厚度的增加,势垒层中其他局域态密度随之增加.在金属电极和Al0.22Ga0.78N势垒层之间加入Si3N4绝缘层可以对表面态起到显著的钝化作用,使表面态密度降为～1012cm-2量级.     

(NH4)2S硫化后ZnS/InP界面的电学特性

在(NH4)2S硫化后的n-型InP衬底上热蒸发ZnS薄膜制得Au/ZnS/InP(100)MIS器件,测得了其I-Ⅴ特性曲线以及3MHz下的高频G-V曲线和100Hz下的准静态G-V曲线.从这些曲线得到如下结果:正向饱和电流为7×10-13A;ZnS钝化下经硫化的n-型InP表面的固定电荷密度为-2.28×1011/cm2;禁带中的最低表面态密度约为1×1012cm-2·eV-1.上述结果表明经硫化后的ZnS/InP界面具有良好的界面特性.     

调制掺杂Al_xGa_(1-x)N/GaN异质结中Al_xGa_(1-x)N势垒层表面态及其他局域态性质研究

通过测量调制掺杂Al0 2 2 Ga0 78N/GaN异质结样品的变频电容电压(C V)特性,对Al0 2 2 Ga0 78N势垒层表面态的性质进行了研究.结果发现在小偏压下,样品的电容随着测量信号频率的增加而下降,说明势垒层中存在表面态.实验数据分析表明:表面态密度约为10 13 cm-2 量级,表面态的时间常数比势垒层中其他局域态大.随着空间隔离层厚度的增加,势垒层中其他局域态密度随之增加.在金属电极和Al0 2 2 Ga0 78N势垒层之间加入Si3 N4绝缘层可以对表面态起到显著的钝化作用,使表面态密度降为～10 12 cm-2 量级     

In0.53Ga0.47As表面氮化和硫钝化对其Al/Al2O3/InGaAs MOS电容特性的影响

本文通过对比频散特性和滞回特性,计算界面态密度D_it和有效边界缺陷密度ΔN_bt,分析界面缺陷和漏电流等方法,系统的研究了In_0.53Ga_0.47As表面氮化和硫钝化对其Al/Al₂O₃/InGaAs结构MOS电容特性的影响。实验结果表明,这两种方法都能够在InGaAs表明形成一层界面钝化层。相比较于未处理的样品,经过氮气等离子体处理的样品表现出较好的界面特性,得到了最小的积累区频散、滞回电压,以及良好的I-V性能。经过(NH₄)₂S_x处理的样品则获得了最小的平带电压区频散以及最低的界面态密度Dit=2.6E11cm_-2eV_-1.     

调制掺杂AlxGa1-xN/GaN异质结中AlxGa1-xN势垒层表面态及其他局域态性质研究

通过测量调制掺杂Al0.22Ga0.78N／GaN异质结样品的变频电容-电压(C-V)特性，对Al0.22Ga0.78N势垒层表面态的性质进行了研究．结果发现在小偏压下，样品的电容随着测量信号频率的增加而下降，说明势垒层中存在表面态．实验数据分析表明：表面态密度约为10^13cm^-2量级，表面态的时间常数比势垒层中其他局域态大．随着空间隔离层厚度的增加，势垒层中其他局域态密度随之增加．在金属电极和Al0.22Ga0.78N势垒层之间加入Si3N4绝缘层可以对表面态起到显的钝化作用，使表面态密度降为～10^12cm^-2量级．     

GaAs/InP键合电学性质的研究

III-V族晶片键合技术对于光电器件的制备和实现光电集成有着重要意义,然而,对于键合界面的电学性质仍然研究较少。采用热电子发射理论,基于界面态能级在禁带中连续分布的假设,根据分布函数结合I-V测试曲线可建立键合结构的界面态计算模型。利用该模型对不同条件下键合的InP/GaAs电学性质做了分析比较,通过初始势垒的确定,计算并比较了各种键合条件下GaAs/InP键合时的界面电荷及界面态密度。实验及计算结果表明疏水处理表面550度条件下键合晶片对有更低的表面初始势垒和更少的界面态密度,因而具有更好的I-V特性。     

中波碲镉汞/钝化层界面电学特性研究

HgCdTe表面/界面特性对器件性能具有重要的影响,表面/界面的状态主要依赖于表面处理和钝化工艺。采用Br2/CH3OH腐蚀液对液相外延(LPE)生长的中波HgCdTe薄膜进行表面处理后,使用Cd Te/Zn S复合钝化技术进行表面钝化,制备了相应的MIS器件并进行器件C-V测试。结果表明,HgCdTe/钝化层界面固定电荷极性为正,面密度为2.1×1011 cm-2,最低快界面态密度为1.43×1011 cm-2·e V-1,在10 V栅压极值下慢界面态密度为4.75×1011 cm-2,较低的快界面态密度体现出了CdTe/ZnS复合钝化技术的优越性。     

Reduction of the surface recombination current in InGaAs/InPpseudo-heterojunction bipolar transistors using a thin InP passivationlayer

In an InGaAs/InP pseudo-heterojunction bipolar transistor (PHBT) with InP passivation, regions from the emitter mesa edge to the base contact are protected by a thin InP barrier layer. By using such a passivation, the surface recombination current is effectively suppressed. The DC current gain obtained for such a PHBT is as high as 455, compared to a maximum value of 240 for a normally passivated PHBT. The current gain is also found to be independent of the perimeter-to-area ratio of the emitter mesa as a result of the passivation     

Fully passivated AR coated InP/InGaAs MSM photodetectors

We report on a technique for antireflection (AR) coating and surface passivation of InP:Fe/InGaAs:Fe metal-semiconductor-metal (MSM) photodetectors using nonreactive radio frequency (RF) magnetron sputtered silicon nitride. Excessive leakage currents and photocurrent gain, major performance-limiting factors of unpassivated detectors, were strongly suppressed in this way. The influence of various chemical pretreatments including sulfide passivation applied to the InP:Fe surface prior to the low-temperature silicon nitride deposition in optimizing the passivating process is investigated     

钝化处理对Al2O3/InP MOS电容界面特性的影响

制备了Al/Al_2O_3/InP金属氧化物半导体(MOS)电容,分别采用氮等离子体钝化工艺和硫钝化工艺处理InP表面。研究了在150、200和300 K温度下样品的界面特性和漏电特性。实验结果表明,硫钝化工艺能够有效地降低快界面态,在150 K下测试得到最小界面态密度为1.6×10¹⁰ cm^-2·eV^-1。与硫钝化工艺对比,随测试温度升高,氮等离子体钝化工艺可以有效减少边界陷阱,边界陷阱密度从1.1×10¹² cm^-2·V^-1降低至5.9×10¹¹ cm^-2·V^-1,同时减少了陷阱辅助隧穿电流。氮等离子体钝化工艺和硫钝化工艺分别在降低边界陷阱和快界面态方面有一定优势,为改善器件界面的可靠性提供了依据。     

Enhancement mode InP MISFET's with sulfide passivation andphoto-CVD grown P3N5 gate insulators

High performance enhancement mode InP MISFET's have been successfully fabricated by using the sulfide passivation for lower interface states and with photo-CVD grown P₃N₅ film used as gate insulator. The MISFET's thus fabricated exhibited exhibited pinch-off behavior with essentially no hysteresis. Furthermore the device showed a superior stability of drain current. Specifically under the gate bias of 2 V for 10⁴ seconds the room temperature drain current was shown to reduce from the initial value merely by 2.9% at the drain voltage of 4 V. The effective electron mobility and extrinsic transconductance are found to be about 2300 cm ²/V·s and 2.7 mS/mm, respectively. The capacitance-voltage characteristics of the sulfide passivated InP MIS diodes show little hysteresis and the minimum density of interface trap states as low as 2.6×10¹⁴/cm² eV has been attained     

Surface-recombination-free InGaAs/InP HBTs and the base contact recombination

Surface-recombination-free InGaAs/InP HBTs with graded base have been demonstrated. The HBTs were passivated by ammonium sulfide. The current gain of the nonself-aligned HBTs was independent of the emitter periphery, indicating that the surface recombination was removed by the passivation. For the self-aligned HBTs, the current gain was still dependent on the emitter periphery after the passivation due to the base contact recombination. A surface leakage channel has been identified to result in a significant increase in the base contact recombination. The passivation has two effects: one is the surface recombination velocity reduction and the other is the surface leakage channel elimination.     

Insulator passivation of In0.2Ga0.8As-GaAssurface quantum wells

The electronic passivation of (100) In_0.2Ga_0.8 As-GaAs surface quantum wells (QWs) using in situ deposition of an amorphous, insulating Ga₂O₃ film has been investigated and compared to standard Al_0.45Ga_0.55As passivation. Nonradiative lifetimes τ_r=1.1±0.2 and 1.2±0.2 ns have been inferred from the dependence of the internal quantum efficiency η on optical excitation density P₀' for the Ga₂O₃ and Al_0.45Ga_0.55As passivated In_0.02 Ga_0.8As-GaAs surface QW, respectively. Beyond identical internal quantum efficiency, the amorphous Ga₂O₃ insulator passivation simplifies device processing, eludes problems arising from lattice-mismatched interfaces, and virtually eliminates band bending in electronic and optoelectronic devices based on a low dimensional system such as quantum wells, wires, and dots     

Hydrogen passivation of defects and impurities in GaAs and InP

Hydrogen passivation experiments in GaAs and InP are discussed. For GaAs it is argued that the results of hydrogen passivation of shallow donors, shallow acceptors and deep centers in materials with different Fermi level positions as well as diffusion data for undoped or lightly doped GaAs are consistent with the assumption that hydrogen is neutral or amphoteric (at least at rather high temperatures of treatment). Some new interesting effects are reported such as improvement of GaAs homogeneity as revealed by microcathodoluminescence imaging and also hydrogen passivation of surface states in GaAs. Evidence is presented that hydrogenation in direct plasmas leads to damage region formation at the surface of the GaAs. A new method of hydrogenation is described that is free from that drawback. The marked improvement of Au/n-GaAs Schottky diodes I-V characteristics is reported after using this method. This new technique is also used to hydrogenate InP for which conventional methods encounter very serious problems. In InP the results of hydrogen passivation experiments on shallow donors and acceptors imply that hydrogen is a deep donor. An interesting effect of injection annealing at room temperature of hydrogen-donor complexes inn-InP is observed.     

Effects of surface passivation during atomic layer deposition of Al2O3 on In0.53Ga0.47As substrates

In this work we investigate the effect of different III-V surface passivation strategies during atomic layer deposition of Al₂O₃. X-ray photoelectron spectroscopy indicates that bare As-decapped and sulfur passivated In_0.53Ga_0.47As present residual oxides on the surface just before the beginning of the Al₂O₃ deposition while the insertion of a Ge interface passivation layer results in an almost oxide free Ge/III-V interface. The study of the initial growth regimes, by means of in situ spectroscopic ellipsometry, shows that the growth of Al₂O₃ on Ge leads to an enhanced initial growth accompanied by the formation of Ge-O-Al species thus affecting the final electrical properties of the stack. Alternatively, deposition on decapped and S-passivated In_0.53Ga_0.47As results in a more controlled growth process. The sulfur passivation leads to a better electrical response of the capacitor that can be associated to a lower oxide/semiconductor interface trap density.     

CaF2 surface passivation of lead selenide grown on BaF2

A new method of surface passivation of PbSe epitaxial layers by growing a thin epitaxial CaF₂ layer is proposed. Improvement in photoluminescence (PL) intensity is observed when the PbSe layer is passivated. The minority carrier lifetime (τ), measured by photo-current decay method corroborates PL measurements and shows a consistent, albeit not considerable, improvement in the lifetime of PbSe samples after surface passivation. The positive effect of surface passivation, especially at low heat-sink temperature, offered by a new passivating material is critically important for IV-VI material-based infrared detector and sensor applications.     

Many body effects in the luminescence of In0.53Ga0.47As/InP quantum wires

We have investigated many body effects in the one-dimensional neutral electron-hole plasma of In_0.53Ga_0.47As/InP quantum wires. By using high laser excitation the active section of the wires was filled up to the InP barrier. The luminescence band shows up to four features which can be assigned to lateral subband transitions in the quantum wires. With increasing excitation intensities we observe a red shift of the emission due to the interparticle interaction among the carriers. By using theoretical line shape calculations the temperature and the density for the electron-hole plasma and the band gap renormalization were determined. The decreasing band gap renormalization with increasing subband index was traced to the density dependence of the exchange energy.