Experimental observation of velocity overshoot in n-channel AlGaAs/InGaAs/GaAs enhancement mode MODFETs

Velocity overshoot phenomena in n-channel AlGaAs/InGaAs/GaAs enhancement mo de MODFETs have been investigated for gate lengths ranging from 1 to 0.5 mu m. The study is based on Motorola's established CGaAs(TM) technology. The o bserved average electron velocity v(av) under the gate is 1,05, 1,34, 1.48, and 1.71 x 10(7) cm/s for a gate length L-G of 1.0.7, 0.6, and 0.5 mum, re spectively. The presence of velocity overshoot in InGaAs channels is clearl y proven with average electron velocities exceeding the steady-state satura tion velocity of congruent to 1 x 10(7) cm/s for LG less than or equal to 0 .7 mum, and with the significant increase of v(av) with shorter gate length .