Short channel effects in submicron self-aligned gate heterostructure field effect transistors

AlGaAs/GaAs self-aligned gate heterostructure FETs with gate lengths varying from 0.3 to 1.5 mu m were fabricated to study short-channel effects. Peak extrinsic transconductance as high as 360 mS/mm was achieved with this process. Short-channel effects such as increases in the output conductance, increases in the subthreshold current, and shifts in the threshold voltage are reported for temperatures ranging from 30 degrees C to 100 degrees C. The observations follow closely predictions from a simple model which attributes the effects to space-charge-limited electron injection into the GaAs buffer layer beneath the actual two-dimensional electron gas channel. >