12 GHz GaAs/InGaAs异质结双栅功率场效应晶体管

报道了GaAs／InGaAs异质结双杨功率场效应晶体管的设计考虑、器件结构和制作，讨论了所采用的一些关键工艺，给出了器件性能。在12GHz下，最大输出功率≥130mW，增益≥12dB，功率附加效率≥30％。     

分子束外延AlGaN/GaN异质结场效应晶体管材料

用自组装的氨源分子束外延 (NH3-MBE)系统和射频等离子体辅助分子束外延 (PA-MBE)系统在 C面蓝宝石衬底上外延了优质 Ga N以及 Al Ga N/Ga N二维电子气材料。Ga N膜 (1 .2 μm厚 )室温电子迁移率达3 0 0 cm2 /V· s,背景电子浓度低至 2× 1 0 1 7cm- 3。双晶 X射线衍射 (0 0 0 2 )摇摆曲线半高宽为 6arcmin。 Al Ga N/Ga N二维电子气材料最高的室温和 77K二维电子气电子迁移率分别为 73 0 cm2 /V·s和 1 2 0 0 cm2 /V· s,相应的电子面密度分别是 7.6× 1 0 1 2 cm- 2和 7.1× 1 0 1 2 cm- 2 ;用所外延的 Al Ga N/Ga N二维电子气材料制备出了性能良好的 Al Ga N/Ga N HFET(异质结场效应晶体管 ) ,室温跨导为 5 0 m S/mm(栅长 1 μm) ,截止频率达 1 3 GHz(栅长 0 .5μm)。该器件在 3 0 0°C出现明显的并联电导 ,这可能是材料中的深中心在高温被激活所致     

用气态源分子束外延生长法制备Si/SiGe/Sinpn异质结双极晶体管

用气态源分子束外延法制备了Ｓｉ／ＳｉＧｅ／Ｓｉｎｐｎ异质结双极晶体管．晶体管基区Ｇｅ组分为０．１２,Ｂ掺杂浓度为１．５e１９ｃｍ－３,ＳｉＧｅ合金厚度约４５ｎｍ．直流特性测试表明,共发射极直流放大倍数约５０,击穿电压ＶＣＥ约９Ｖ;射频特性测试结果表明,晶体管的截止频率为７ＧＨｚ,最高振荡频率为２．５ＧＨｚ．     

用气态源分子束外延生长法制备Si/SiGe/Si nPn异质结双极晶体管

用气态源分子束外延法制备了Si/SiGe/Si npn异质结双极晶体管.晶体管基区Ge组分为0.12,B掺杂浓度为1.5×101 9cm-3, SiGe合金厚度约45nm.直流特性测试表明,共发射极直流放大倍数约50,击穿电压VCE约9V;射频特性测试结果表明,晶体管的截止频率为7GHz,最高振荡频率为2.5GHz.     

As/P气氛转换对InGaAs/InP异质结界面的影响研究

采用分子束外延（MBE）方法,在半绝缘InP（100）衬底上外延InGaAs/InP超晶格结构。通过优化As、P转换时间,研究了As、P气氛转换对InGaAs/InP异质结界面特性的影响。经原子力显微镜测试和X射线衍射谱分析,样品在关P阀5 s、开As阀5 s的生长条件下,表面均方根粗糙度（RMS）为0.205 nm,单边卫星峰达20级,一级卫星峰的半高宽（FWHM）为145.05 arc sec ,表明界面控制良好。     

利用全固态分子束外延方法在Ge(100)衬底上异质外延GaAs薄膜及相关特性表征

利用全固态分子束外延(MBE)方法在Ge(100)衬底上异质外延GaAs薄膜,并通过高能电子衍射(RHEED)、高分辨X射线衍射(XRD),原子力显微镜等手段研究了不同生长参数对外延层的影响.RHEED显示在较高的生长温度或较低的生长速率下,低温GaAs成核层呈现层状生长模式.同时降低生长温度和生长速率会使GaAs薄膜的XRD摇摆曲线半高宽(FWHM)减小,并降低外延层表面的粗糙度,这主要是由于衬底和外延薄膜之间的晶格失配度减小的结果.     

SiGe/Si异质结双极晶体管研究

介绍了一咱ＳｉＧｅ／Ｓｉ分子束外延异质结双极晶体管（ＨＢＴ）的研制。该器件采用３μｍ工艺制作,测量得其电流放大系数β为５０,截止效率ｆｒ为５．１ＧＨｚ,表明器件的直流特性和交流特性良好。器件的音片成品率在９０％以上。     

MBE生长InGaAs／GaAs应变层单量子阱激光器结构材料的研究

采用ＶａｒｉａｎＧｅｎⅡＭＢＥ生长系统研究了ＩｎＧａＡｓ／ＧａＡｓ应变层单量子阶（ＳＳＱＷ）激光器结构材料。通过ＭＢＥ生长实验，探索了Ｉｎ＿ｘＧａ＿（１－ｘ）ｔＡｓ／ＧａＡｓＳＳＱＷ激光器发射波长（λ）与Ｉｎ组分（ｘ）和阱宽（Ｌ＿ｚ）的关系，并与理论计算作了比较，两者符合得很好。还研究了材料生长参数对器件性能的影响，主要包括：Ⅴ／Ⅲ束流比，量子阱结构的生长温度Ｔ＿ｇ（ＱＷ），生长速率和掺杂浓度对激光器波长、阈值电流密度、微分量子效率和器件串联电阻的影响。以此为基础，通过优化器件结构和ＭＢＥ生长条件，获得了性能优异的Ｉｎ＿（０．２）Ｇａ＿（０．８）Ａｓ／ＧａＡｓ应变层单量子阱激光器：其次长为９６３ｎｍ，阈值电流密度为１３５Ａ／ｃｍ￣２，微分量子效率为３５．１％。     

GaAs/InGaAs应变异质结构临界厚度的Raman散射和PL谱分析

采用室温Raman散射和低温光致发光(PL)谱,对以TMG,固体As和固体In作为分子束源的MOMBE法生长的GaAs/In_xGa_(1-x)As(x=0.3)单层异质结构和多量子阱结构中InGaAs应变层的临界厚度进行了实验研究。由应变引起的Raman散射峰位移,以及PL谱峰位置与应变和无应变状态下一维有限深势阱跃迁能量计算结果的比较可见,在In组分含量x=0.3的情况下,临界厚度H_c≤5nm,小于能量平衡理论的结果,而与力学平衡模型的理论值相近。     

Investigation of the band structure of the strained systems InGaAs/GaAs and InGaAs/AIGaAs by high-pressure photoluminescence

In_xGa_1-xAs quantum wells grown pseudomorphically in GaAs and AlGaAs with values ofx up to 0.25 have been studied by photoluminescence under high hydrostatic pressure. We concentrate here on the pressure range where the emissions quench and take on the characteristics of theX-minima. In the InGaAs/GaAs structures, these transitions display an unexpected pressure coefficient, -2.6 meV/kbar, twice that of theX minima in GaAs. We assign these transitions to theX minima in the wells, and therefore make a direct measurement of the strainedX positions as a function of composition. In the InGaAs/AIGaAs structures the crossovers occur against theX-minima in the barriers and these crossovers yield an accurate value for the band offset ratio for InGaAs/GaAs heterojunctions which is found to be 60:40 (CB:VB).     

Comparison of InGaSb/InAs superlattice structures grown by MBE on GaSb, GaAs, and compliant GaAs substrates

This paper contains the characterization results for indium arsenide/indium gallium antimonide (InAs/InGaSb) superlattices (SL) that were grown by molecular beam epitaxy (MBE) on standard gallium arsenide (GaAs), standard GaSb, and compliant GaAs substrates. The atomic force microscopy (AFM) images, peak to valley (P-V) measurement, and surface roughness (RMS) measurements are reported for each sample. For the 5 μm×5 μm images, the P-V heights and RMS measurements were 37 ? and 17 ?, 12 ? and 2 ?, and 10 ? and 1.8 ? for the standard GaAs, standard GaSb, and compliant GaAs respectively. The high resolution x-ray diffraction (HRXRD) analysis found different 0^th order SL peak to GaSb peak spacings for the structures grown on the different substrates. These peak separations are consistent with different residual strain states within the SL structures. Depending on the constants used to determine the relative shift of the valance and conduction bands as a function of strain for the individual layers, the change in the InAs conduction band to InGaSb valance band spacing could range from +7 meV to −47 meV for a lattice constant of 6.1532 ?. The cutoff wavelength for the SL structure on the compliant GaAs, control GaSb, and control GaAs was 13.9 μm, 11 μm, and no significant response, respectively. This difference in cutoff wavelength corresponds to approximately a −23 meV change in the optical gap of the SL on the compliant GaAs substrate compared to the same SL on the control GaSb substrate.     

Growth and characterization of (111)B InGaAs/GaAs multi-quantum well PIN diode structures

High quality piezoelectric strained InGaAs/GaAs multi-quantum well structures on (111)B GaAs substrates have been grown by solid-source molecular beam epitaxy in a PIN configuration. 10K photoluminescence (PL) shows narrow peaks with widths as low as 3 meV for a 25-period structure while room temperature (RT) PL shows several higher order peaks, normally forbidden, indicating breaking of inversion symmetry by the piezoelectric field. Furthermore, both the 10K PL peak position and the form of the RT PL spectra depend on the number of quantum wells within the intrinsic region, suggesting that the electric-field distribution is altered thereby. Diodes fabricated from these structures had sharp avalanche breakdown voltages (V_bd) and leakage currents as low as 8 × 10⁻⁶ A/cm² at 0.95 V_bd, indicating quality as high as in (100) devices. On leave from: Department de Ingeniera Electronica, Universidad Politecnica de Madrid, Madrid, Spain.     

Structural and infrared absorption properties of self-organized InGaAs/GaAs quantum dots multilayers

Self-organized InGaAs/GaAs quantum dots (QDs) stacked multilayers have been prepared by solid source molecular beam epitaxy. Cross-sectional transmission electron microscopy shows that the InGaAs QDs are nearly perfectly vertically aligned in the growth direction [100]. The filtering effect on the QDs distribution is found to be the dominant mechanism leading to vertical alignment and a highly uniform size distribution. Moreover, we observe a distinct infrared absorption from the sample in the range of 8.6–10.7 μm. This indicates the potential of QDs multilayer structure for use as infrared photodetector.     

TEM study of the effect of growth interruption in MBE of InGaP/GaAs superlattices

The influence of growth interruption during the MBE growth of (100) In_0.5Ga_0.5P/GaAs superlattices is investigated by cross-sectional TEM. A roughening of the growth front is observed during an interruption after the exchange of the group-V molecular beams. The roughening of growth front occurs due to a spontaneous change in the growth orientation of the superlattice from [100] to 〈311〉 directions. This change in growth orientation is characterized by an initial formation of V-shaped grooves with {311} facets on the GaAs growth front which eventually lead to the formation of regions of {311} superlattice structures. The direction of V-shaped grooves is along the [011] axis, which is parallel to the surface dangling bonds of the group V atoms in the unreconstructed (100) plane. The most critical stage for the spontaneous change of the growth orientation is the interruption after the growth of a GaAs layer with the P₂ flux.     

应变超晶格In_(0.15)Ga_(0.85)As/GaAs的电镜和光谱研究

用光调制反射谱和透射电镜技术研究分子束外延生长的应变超晶格In_(0.15)Ga_(0.85)As/GaAs,并讨论了实验结果。     

Critical thickness of GaAs/InGaAs and AlGaAs/GaAsP strained quantum wells grown by organometallic chemical vapor deposition

In this paper we describe a study of strained quantum wells (QWs) as a means to experimentally observe the critical thickness (h _c) for the formation of interfacial misfit dislocations. Two material systems were investigated: GaAs/In_0.11Ga_0.89As, in which the QW layers are under biaxialcompression, and Al_0.35Ga_0.65As/GaAs_0.82P_0.18, in which the QW layers are under biaxialtension. Samples were grown by atmospheric pressure organometallic chemical vapor deposition, and characterized by low-temperature photoluminescence (PL), x-ray diffraction, optical microscopy, and Hall measurements. For both material systems, the observed onset of dislocation formation agrees well with the force-balance model assuming a double-kink mechanism. However, overall results indicate that the relaxation is inhomogeneous. Annealing at 800–850° C had no significant effect on the PL spectra, signifying that even layers that have exceededh _c and have undergone partial relaxation are thermodynamically stable against further dislocation propagation.