CRYOGENIC INVESTIGATION OF GATE LEAKAGE AND RF PERFORMANCES DOWN TO 50K OF 0.2-MU-M ALLNAS GAINAS/INP HEMTS/

0.2mum Al0.48In0.52As/Ga0.47In0.53As LMHEMT on InP with an undoped GaI nAs layer to reduce gate leakage have been realised and their DC and R F properties have been investigated at cryogenic temperatures. The cut off maximum frequencies of oscillation F(max) up to 260Hz are extrapol ated at 50K from the maximum unilateral gain (MUG) determined using S parameters measured up to 40GHz. Evolution of gate leakage current and RF characteristics against gate and drain biases are presented betwee n 50 and 300K.