High-performance Ga0.51In0.49P/GaAs airbridge gate MISFET´s grown by gas-source MBE

Ga_0.51In_0.49P/GaAs MISFET´s, in which Ga_0.51In_0.49P insulating layer was inserted between the gate metal and the channel layer, were compared with MESFET´s experimentally and theoretically in terms of DC and microwave performance. Devices performance were evaluated by varying the thickness of the insulating layer. Wide and flat characteristics of g_m, g_t, and f_max versus drain current (or gate voltage) together with a high maximum current density (above 610 mA/mm) were achieved for devices with insulating layer thickness of 50 mn and 100 mm. Moreover, the maximum values of J_t´s and f_max ´s for a 1-μm gate length device both occurred when t was between 50 and 100 mn. We also observed that parasitic capacitances and gate leakage currents were minimized by using the airbridge gate structure, and thus high-frequency and breakdown characteristics were greatly improved, These results demonstrate that Ga_0.51In_0.49P/GaAs airbridge gate MISFET´s with insulating layer thickness between 50 and 100 mn were very suitable for microwave high-power device applications