摘要
用国产分子束外延设备(Ⅳ型),在低温(200—300℃)下生长了GaAs,AlGaAs和GaAs-AlGAs超晶格。本文着重提出对在低温生长GaAs缓冲层上生长优质GaAs有源层,尤其对缺陷和杂质很敏感的高电子迁移率晶体管结构材料进行研究。
Low temperature growth of GaAs as a buffer layer with resistivity of 10~6Ω·cm and opticallyinactive was grown in a home-made MBE system under arsenic-stable growth conditionsat substrate temperatures ranging from 200℃ to 300℃ and at growth rate of 1μm/h. The reflected high energy electron diffraction pattern was minitored during growth. AlthoughLT-GaAs layer signicantly reduce the sidegating, it can adversely affect the materialquality due to the diffusion of defects from LT-GaAs into the active layer. A medium layer is inserted between the active layer and LT-GaAs layer. GaAs-AlGaAssuperlattice is suggested to prevent the defect diffusion. A relatively small photolumimescencelinewidth of 9 meV and high Hall mobility of 10~5 cm^2/V. s at 77K indicate the highquality material similar to that of sample without the LTBL.
