Silicon-germanium power devices at low temperatures for deep-space applications

Silicon-germanium heterostructure. based 1-watt n-channel metal-oxide-semiconductor modulation-doped field effect transistors (MOS-MODFETs) with 6 μm gate lengths and 1 mm total gate widths have been designed, fabricated and tested from 300 K to 90 K. The devices were fabricated by an ion-implanted process and employ a low-temperature thermal oxide and PECVD deposited oxide as the gate insulator. The devices showed a saturation current of approximately 77 mA at V_DS=14 V, V_GS=5V at 90 K, corresponding to a power dissipation of 1 W. Because they employ oxide as a gate dielectric, the devices have a low gate leakage current of <1 nA at V_GS=10 V.