Novel high performance self-aligned 0.15 micron long T-gate AlInAs-GaInAs HEMTs

A novel self-aligned technique for 0.15- mu m-gate-length HEMTs (high electron mobility transistors) has been demonstrated. This technology uses a 0.15- mu m-long T-gate structure defined by e-beam lithography with a SiO/sub 2/ sidewall to implement the self-aligned scheme. The resultant device has low source and drain resistances, low gate resistance (200 Omega /mm), and a passivating layer over the active channel. Devices with an oxide sidewall yielded an f/sub T/ of 177 GHz, whereas devices with no sidewall exhibited an f/sub T/ greater than 250 GHz. The difference has been related to process damage during plasma deposition of SiO/sub 2/.<
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