INVESTIGATION OF LOW-TEMPERATURE (LT) LAYERS OF GAAS GROWN BY MBE - COMPARISON OF MESFET AND HEMT PERFORMANCE

GaAs buffer layers grown on GaAs (100) by MBE and modulated flux MBE ( MF MBE) were investigated using substrate temperatures between 200 and 600-degrees-C, growth rate 1 mum/h and equivalent pressure ratio P(As 4)/P(Ga) = 7-17. The growth process was investigated by RHEED observat ion, crystallinity of samples by electron channelling pattern (ECP) an d surface morphology by scanning electron microscopy (SEM). LT layers have been incorporated as buffer layers in MESFET and HEMT structures in order to eliminate sidegating, kink effect and hysteresis in the I - V characteristics. Comparison has been made between MESFETs and HEMT s incorporating LT buffer layers, SL buffer layers and p-AlGaAs buffer layers.