High-quality metamorphic HEMT grown on GaAs substrates by MBE

摘要

Metamorphic high electron mobility transistor (M-MEMT) structures have been grown on GaAs substrates by molecular beam epitaxy (MBE). Linearly graded and the step-graded InGaAs and InA1As buffer layers have been compared, and TEM, PL and low-temperature Hall have been used to analyze the properties of the buffer layers and the M-HEMT structure. For a single-delta-doped M-HEMT structure with an In_0.53Ga_0.47As channel layer and 0.8 μm Step-graded InA1As buffer layer, room-temperature mobility of 9000 cm~2/V s and a sheet electron density as high as 3.6×10~12/cm~2 are obtained. These results are nearly equivalent to those obtained for the same structure grown on an InP substrate. A basic M-HEMT device with 1 μm gate was fabricated, and g_m is larger than 400 mS/mm.