高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长

用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份Al_xGa_1-xAs（其x值达0.83）,和Al_xGa_1-xAs/GaAs/Al_xGa_1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n_300K=1.7×10¹⁵cm^-3,n_77K=1.4×10¹⁵cm^-3,迁移率μ_300K=5900cmcm²/V.S,μ_77K=55500cm²/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。

INVESTIGATION OF MOCVD GROWTH OF AIxGa1-x As/GaAs AND AlxGa1-x As/GaAs/ AlxGa1-x As/GaAsMULTILAYER STRUCTURE WITHHIGH Al COMPOSITION

Mirrorlike surface Al_xGa_1-x As/GaAs and Al_xGa_1-x As/GaAs/Al_xGa_1-x As/GaAs multilayer structure with high composition of Al(x= 0.83) grown on a semiinsulating GaAs substrate are obtained in a selfmade atmospheric pressure MOCVD system. The smooth interface between epilayers of Al_xGa_1-xAs and GaAs are observed using SEM cross section technique. The x value of Al_xGa_1-xAs can be widely adiusted from a small x up to x=0.83. The high quality of GaAs and Al_xGa_1-xAs epilayers has been approved by the Double Crystal X-ray rocking curve, where one peak stands for the two epilayers of Al_xGa_1-x As, another stands for GaAs epilayer and GaAs substrate.High purity GaAs with n_300k= 1.7×10¹⁵cm^-3,μ_300k=5900cm²/V·s, n_77k= 1.4× 10¹⁵cm^-3, μ_77k= 55500cm²/V·s has been routinely achieved. Contamination is not detected from AES and Electron Probe measurements, while very small peaks of Si and C are seen on photoluminescence spectra.Epilayer surface defects, leaning angles of the substrates, growth temperatures and other growth conditions are also studied in details.