注入Ga离子的GaAs／AlGaAs量子阱中界面混合的光荧光研究

用注入Ｇａ离子ＧａＡｓ／ＡｌＧａＡｓ量子阱在快速热退火中大大加快了异质结界面的互扩散，表现在ＰＬ光谱中量子阱峰值能量有３０～９０ｍｅＶ的兰移．发现兰移大小同注入损伤程度、退火的温度及时间有关，并得到快速退火中的互扩散系数Ｄ约为１０－１５～１０－１７ｃｍ２／ｓ     

应用Volterra级数分析AlGaAs/GaAsHBT的三阶互调失真

分析了AlGaAs／GaAsHBT的非线性失真产生的机理,应用Volterra级数理论计算了AlGaAs／GaAsHBT的三阶互调失真,理论值与实测值吻合较好,获得了AlGaAs／GaAsHBT的非线性失真量比较弱的结果,其值并不像人们认为的那样强,并解释了HBT高线性度的原因,这证明了AlGaAs／GaAsHBT在抗干扰方面的潜在能力。     

插入生长AlGaAs薄膜对InAs量子点探测器性能的影响

利用分子束外延生长获得的两个InAs量子点样品制备了n型的量子点红外探测器.对于其中一个器件，在InAs量子点有源区的底部和顶部分别插入生长了AlGaAs势垒层.利用透射电阻显微技术研究了两个样品的结构特性；利用光致发光光谱和光电流谱研究了两个器件的光电性质.实验结果表明，AlGaAs层的插入对器件的探测性质有显著的影响.利用有三维效质量近似模型的计算结果，指认了带内光电流谱中峰结构的起源.     

RTA removal of E-beam-induced damage in GaAs-AlGaAs heterostructures as determined by magnetotransport characterization

Measurement was made of the effect of electron energy on the 2D EG transport properties of high electron mobility transistor (HEMT) structures at low temperatures. The structures were grown by molecular beam epitaxy (MBE) with a 2D EG approximately 850Å below the surface. A Cambridge EBMF 10.5 was used for electron irradiation with electron energies between 2.5 and 20 keV. The HEMTs were fabricated into Hall bars, and damage was assessed by changes in the 2D EG concentrations as determined from Shubnikov-de Haas oscillations and changes in the mobility as determined from the zero magnetic-field resistivity. For electron energies from 5.0 to 12.5 keV, the electron dose produced a degradation of the Hall mobility. No damage was observed for electron energies outside this range; this result is attributed to the penetration depth and damage distribution. The effect of performing RTA on all samples simultaneously at 450° C for 30 sec was to remove damage and in some cases restore the sample to its original mobility.     

Effect of edges on the reliability of GaAs and (AlGa) as heterojunction leds

The effect of various diode geometries on the degradation rate of heterojunction diodes with either GaAs or (AlGa)As in the recombination region has been studied. It is shown that GaAs diodes are particularly sensitive to edge-related degradation which varies with the current density J as J^3/2. The addition of Al to the recombination region considerably reduces the degradation rate of diodes both with and without exposed edges, and data are reported for Al_0.1Ga_0.9As stripe-contact edge-emitting structures operating for over 20,000 hours with no change in output at 1000 A/cm².     

Influence of oxygen in AlGaAs-based laser structures with Al-Free active region on device properties

AlGaAs-based lasers with GaAsP active regions for emission wavelengths near 730 nm and 800 nm were studied. Trimethyl aluminum sources with different levels of oxygen concentration were used for the deposition of the laser structures. The laser data show that the oxygen level in the AlGaAs wave guides is very critical for the performance of the 730 nm devices, even for the use of an Al-free active region, while its influence is weak for the 800 nm devices. Using the TMAl source leading to the lowest O-uptake in the AlGaAs wave guides from such structures, 7 W output power and a degradation rate of 1 10⁻⁵h⁻¹ at 2 W cw (100 μm stripe width × 4 mm, 25°C, 2000 h) are achieved for 730 nm emission.     

Uniform Descriptions of Electron-IO Phonon Interaction in Structures of Multi-layer Coupling Low-dimensional Systems

By using the transfer matrix method, within the framework of the dielectric continuum approximation, uniform forms for the interface optical (IO) phonon modes as well as the corresponding electron-IO phonon interaction Hamiltonians in n-layer coupling low-dimensional systems (including the coupling quantum well (CQW), coupling quantum-well wire (CQWW), and coupling quantum dot (CQD)) have been presented. Numerical calculations on the three-layer asymmetrical AlGaAs/GaAs systems are performed, and the analogous characteristics for limited frequencies of IO phonon in the three types of systems (CQW, CQWW, and CQD) when the wave-vector and the quantum number approach zero or infinity are analyzed and specified.     

GaAs和AlGaAs MBE外延生长动力学研究

研究了在ＧａＡｓ（００１）衬底上外延生长ＧａＡｓ、ＡｌＧａＡｓ材料过程中反射高能电子衍射（ＲＨＥＥＤ）的各级条纹及其强度随生长过程的变化。通过对各级条纹强度振荡周期和位相的分析,应用二维成核层状生长模型解释了实验结果：生长表面形貌的周期性变化导致了ＲＨＥＥＤ各级条纹及其强度的周期性变化。     

基于循环退火技术的InGaAs/AlGaAs量子阱混杂

为了解决由于激光器腔面处的光吸收引起的腔面光学灾变损伤(COD),采用无杂质空位扩散(IFVD)法,研究了由SiO2电介质层诱导的InGaAs/AlGaAs量子阱结构的带隙蓝移。使用等离子化学气相沉积(PECVD)在InGaAs/AlGaAs量子阱的表面生长SiO2电介质层;然后采用IFVD在N2环境下进行高温退火实验,从而实现量子阱混杂(QWI)。实验结果表明:蓝移量的大小随退火时间和电介质层厚度的变化而变化,样品覆盖的电介质层越厚,在相同的退火温度下承受的退火时间越长,得到的蓝移量也越大。然而,在高温退火中的时间相对较长时,退火对量子阱造成的损坏相当大。高温短时循环退火,能够在保护量子阱晶体质量的同时实现QWI。通过在850℃退火6min下循环退火5次,得到了46nm的PL蓝移,且PL峰值保持在原样品的80%以上。     

Anomalous dephasing of two-dimensional electrons in an AlGaAs/GaAs parabolic quantum well structure

Magnetoconductivity measurements are performed on a parabolic quantum well structure. The weak localization effect is observed at a low magnetic field for both single-subband and double-subband occupation regimes. Applying weak-localization theory, we have extracted the dephasing rate. The extracted dephasing rate increases with increasing conductivity in the small-energy-transfer regime and shows a similar trend as the electron density is increased in the large-energy-transfer regime. This is in conflict with Fermi-liquid theory, and cannot be attributed to electron–phonon scattering.