INVESTIGATION OF ALXGAYIN1-X-YP AS A SCHOTTKY LAYER OF ALINAS GAINAS HIGH-ELECTRON-MOBILITY TRANSISTORS/

The use of high band gap strained AlxGayIn1_x_yP as a Schottky layer o f AlInAs/GaInAs high electron mobility transistors on InP has been inv estigated. A Schottky layer with a small AIP mole fraction (Al0.1Ga0.1 In0.8P or Al0.2In0.8P) significantly increases the Schottky barrier he ight, leading to significant reduction of gate leakage currents. Devic es with an Al0.2In0.8P Schottky layer yield gate breakdown voltages as high as -15.5 V in addition to improving drain breakdown voltages (si milar to 8 V). With devices having a gate length of 0.5 mu m, we have achieved a maximum transconductance (g(m)) of 480 mS/mm, current gain cutoff frequency (f(T)) Of 68 GHz, and power gain cutoff frequency (f( max)) of 130 GHz.