Both GaInP/In0.2Ga0.8As and AlInP/In0.2Ga0.8As HEMT's were fabricated with WSix gates and evaluated at high temperature operations. Based on the high stability of WSix gates, both devices functioned at temperature up to 300 degrees C. GaInP HEMT's showed a g(m) reduction from 176 mS/mm at 25 degrees C to 97 mS/mm at 300-degrees C, while V-th shifted from -1.44 V to -3.31 V. AlInP HEMT's also showed a g(m) decrease from 135 mS/mm at 25 degrees C to 70 mS/mm at 300 degrees C, while V-th shifted from -0.4 V to -0.84 V. Both of these devices with WSix gates offer a potential applications to high power and high temperature operations.
