溅射ZnO薄膜钝化GaAs表面性能的研究

为了改善GaAs(110)与自身 氧化物界面由于高表面态密度而引起的费米能级钉扎(pinning)问题 ,提出采用射频磁控溅射技 术在GaAs(110)衬底上沉积一定厚度 ZnO薄膜作为钝化层,并利用光 致发光(PL)光谱和X射线光电子能谱(XPS) 等方法对ZnO薄膜的光学特性及钝化性能进行表征。实验结果表明,经ZnO薄膜钝化后的 GaAs样品,其本征PL峰强度提高112.5%,杂质峰强度下降82.4%。XPS光谱分析表明,Ga和As原子的比值从1.47降低 到0.94,ZnO钝化层能 够抑制Ga和As的氧化物形成。因此,在GaAs表面沉积ZnO薄膜是一种可行的GaAs表面钝化 方法。     

硫化物钝化GaAs表面的研究进展

叙述用硫钝化GaAs表面的研究动态,包括表面处理工艺,已取得的效果及表面钝化的机理,并指出今后的研究内容。     

GaAs经硫和硒钝化处理后的光致发光

研究了用Ｎａ＿２Ｓ·９Ｈ＿２Ｏ，（ＮＨ＿４）＿２Ｓ＿ｘ和Ｓｅ钝化的ＧａＡｓ的光致发光。这种钝化是经湿法化学处理来进行的。硫和硒处理后，我们观察到光致发光强左有明显的增强。同时我们也比较了三种钝化方法的效果。经分析认为，这种增强是由于表面复合中心密度的减小而造成的。     

β-GaS钝化的GaAs表面的光电子能谱

在GaAs表面淀积β-GaS是一种可行的GaAs表面钝化方法.用光电子能谱研究了超薄GaS淀积后的GaAs表面,分析了表面成分.并发现GaS的淀积能使GaAs原有的表面能带弯曲减小0.4eV,这意味着表面费米能级钉扎在一定程度上得到消除.给出了一个半定量的理论模型,来解释GaS淀积引起的能带弯曲减小与以前湿法钝化引起的能带弯曲增大之间的不同.     

β-GaS钝化的GaAs表面的光电子能谱

在 Ga As表面淀积β- Ga S是一种可行的 Ga As表面钝化方法 .用光电子能谱研究了超薄Ga S淀积后的 Ga As表面 ,分析了表面成分 .并发现 Ga S的淀积能使 Ga As原有的表面能带弯曲减小 0 .4e V,这意味着表面费米能级钉扎在一定程度上得到消除 .给出了一个半定量的理论模型 ,来解释 Ga S淀积引起的能带弯曲减小与以前湿法钝化引起的能带弯曲增大之间的不同     

硫化的激光器腔面上溅射ZnS钝化膜的研究

提出了一种新的激光器腔面钝化方法.先用(NH4)2S溶液硫化解理后的激光器腔面,然后使用磁控溅射方法对激光器的前腔面镀ZnS钝化膜、后腔面镀Si/SiO2高反射膜.ZnS钝化层光学厚度为λ/4,在中心波长为808 nm处透过率可达95.5%.钝化前激光器的光学灾变损伤(COD)阈值为1.6 W,钝化后为2.0 W,提高了25%倍;未镀膜的激光器阈值电流为0.25 A,经硫化再镀ZnS后阈值电流为0.20 A,降低了20%.实验结果表明,经硫化后溅射ZnS对激光器腔面具有良好的钝化和增透效果.     

单量子阱GaAs/AlGaAs半导体激光器

本文介绍了用分子束外延法制作的梯度折射率分别限制式单量子阱GaAs/AlGaAs半导体激光器。该器件具有较低的阈值电流密度和单模运转特性,连续输出功率可达55mw。     

用于GaAs功率MESFET的新型钝化膜

用直流反应溅射淀积的AlN薄膜对GaAs功率MESFET进行了钝化。给出了钝化后器件的直流特性。器件的直流参数BVGD、IDSS和Vp在钝化后几乎没有改变。还给出了器件的微波特性。实验证明，AlN钝化的器件性能较好，它是一种很有前途的GaAs钝化材料。     

改善GaAs MESFETs硫钝化稳定性研究的新探索

硫钝化可以明显改善GaAs金属半导体场效应晶体管(MESFETs)的击穿特性,但钝化效果不稳定。我们利用硫钝化和PECVDSiNr钝化相结合的方法,使钝化的稳定性得到了提高,但同时击穿电压会出现下降。击穿电压下降的主要原因是：As-S键很不稳定,在较高温度下分解,使GaAs表面负电荷密度减小,击穿电压下降。     

表面钝化技术对光学灾变的影响的研究

介绍了对半导体激光器的腔面进行钝化处理的方法,分别采用几种不同的试剂对腔面进行处理,得出不同的结果。实验表明,用P2S5/NH4OH和(NH4)2Sx共同处理的样品在较高功率时开始发生光学灾变。     

Determination of the Band Offset of GalnP- GaAs and AllnP- GaAs Quantum Wells by Optical Spectroscopy

We report the determination of band offset ratios, using photoluminescence excitation measurements, for GaInP/GaAs and AlInP/GaAs quantum wells grown by gas-source molecular beam epitaxy. To reduce the uncertainty related to the intermixing layer at heterointerfaces, the residual group-V source evacuation time was optimized for abrupt GalnP/GaAs (AlInP/GaAs) interfaces. Based upon thickness and composition values determined by double-crystal x-ray diffraction simulation and cross-sectional transmission electron microscopy, the transition energies of GalnP/GaAs and AlInP/GaAs quantum wells were calculated using a three-band Kane model with varying band-offset ratios. The best fit of measured data to calculated transition energies suggests that the valence-band offset ratio (γ band discontinuity) was 0.63 ± 0.05 for GalnP/GaAs and 0.54 ± 0.05 for AlInP/GaAs heterostructures. This result showed good agreement with photoluminescence data, indicating that the value is independent of temperature.     

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.     

Surface photoabsorption monitoring of the growth of GaAs and InGaAs at 650°C by MOCVD

By monitoring the cyclic behavior of surface photoabsorption (SPA) reflectance changes during the growth of GaAs at 650°C and with sufficient H₂ purging time between the supply of trimethylgallium and AsH₃, we have been able to achieve controlled growth of GaAs down to a monolayer. Our results show, as confirmed by photoluminescence (PL) measurements, the possibility of growing highly accurate quantum well heterostructures by metalorganic chemical vapor deposition at conventional growth temperatures. We also present our PL measurements on the InGaAs single quantum wells grown at this temperature by monitoring the SPA signal.     

Hydrogen plasma passivation of bulk GaAs and Al0.3Ga0.7As/GaAs multiple-quantum-well structures on Si substrates

Hydrogen (H) plasma passivation effects on GaAs grown on Si substrates (GaAs on Si) are investigated in detail. H plasma exposure effectively passivates both the shallow and deep defects in GaAs on Si, which improves both the electrical and optical properties. It was found that the minority carrier lifetime is increased and the deep level concentration is decreased by the H plasma exposure. In addition, after H plasma exposure, room temperature photoluminescence (PL) for Al_0.3Ga_0.7As/GaAs multiple-quantum-well (MQW) on Si is enhanced with a decrease in the spectral width.     

大功率半导体激光器的腔面钝化

大功率半导体激光器的腔面退化是影响其寿命和可靠性的重要因素,长期以来一直是人们关注和研究的重点。本文利用离子铣结合腔面钝化还原层的方法对大功率半导体激光器的腔面进行处理。结果显示,离子铣腔面钝化能够在一定程度上减少半导体激光器的功率退化,168h加速老化后退化幅度降低4.5%;同时该技术对老化过程中COD阈值降低有明显的抑制作用,可有效减少使用中的突然失效。结果表明,该技术能够改善半导体激光器的腔面特性,器件的可靠性和使用寿命可望得到提高。     

Carbon doped GaAs grown in low pressure-metalorganic vapor phase epitaxy using carbon tetrabromide

Carbon tetrabromide was used as carbon source for heavily p-doped GaAs in low pressure metalorganic vapor phase epitaxy (MOVPE). The efficiency of carbon incorporation was investigated at temperatures between 550 and 670°C, at V/III ratios from 1 to 50 and carbon tetrabromide partial pressures from 0.01 to 0.03 Pa. Hole concentrations from 8 × 10¹⁷ to 5 × 10¹⁹ cm⁻³ in as-grown layers were obtained. After annealing in nitrogen atmosphere at 450°C, a maximum hole concentration of 9 × 10¹⁹ cm⁻³ and a mobility of 87 cm²/Vs was found. At growth temperatures below 600°C, traces of bromine were detected in the layers. Photoluminescence mapping revealed an excellent doping homogeneity. Thus, CBr₄ is found to be a suitable carbon dopant source in MOVPE.     

Deep level electronic structure of ZnSe/GaAs heterostructures

We performed 1—2 keVcathodoluminescence measurements and He-Ne and HeCd excited photoluminescence studies of ZnSe/GaAs( 100) heterostructures grown by molecular beam epitaxy. Our goal was to investigate the deep level electronic structure and its connection with the heterojunction band offsets. We observed novel deep level emission features at 0.8, 0.98, 1.14, and 1.3 eV which are characteristic of the ZnSe overlayer and independent in energy of overlayer thickness. The corresponding deep levels lie far below those of the near-bandedge features commonly used to characterize the ZnSe crystal quality. The relative intensity and spatial distribution of the deep level emission was found to be strongly affected by the Zn/Se atomic flux ratio employed during ZnSe growth. The same flux ratio has been shown to influence both the quality of the ZnSe overlayer and the band offset in ZnSe/GaAs heterojunctions. In heterostructures fabricated in Se-rich growth conditions, that minimize the valence band offset and the concentration of Se vacancies, the dominant deep level emission is at 1.3 eV. For heterostructures fabricated in Zn-rich growth conditions, emission by multiple levels at 0.88,0.98, and 1.14 eV dominates. The spectral energies and intensities of deep level transitions reported here provide a characteristic indicator of ZnSe epilayer stoichiometry and near-interface defect densities.