HIGH-TRANSCONDUCTANCE P-CHANNEL MODULATION-DOPED AlGaAs/GaAs HETEROSTRUCTURE FET'S.

The authors report the fabrication of p-channel modulation-doped AlGaAs-GaAs heterostructure FETs (p-HFETs) using two-dimensional hole gas (2DHG) under various geometrical device parameter conditions. The p-HFET characteristics were measured at 300 and 77 K for the following three device-parameter ranges: the gate length L//g (1-320 mu m), the gate-source distance L//g //s (0. 5-5 mu m), and the layer thickness d//t (35-58 nm) of AlGaAs beneath the gate. Based on the obtained results, a high-performance enhancement-mode p-HFET was fabricated with the following parameters: L//g equals 1 mu m, L//g //s equals 0. 5 mu m, and d//t equals 35 nm. The achieved extrinsic transconductance g//m was 75 mS/mm at 77 K. This experimental result indicates that a g//m greater than 200 mS/mm at 77 K can be obtained in 1- mu m gate p-HFET devices.