A self-aligned gate pseudomorphic high-electron-mobility transistor (PHEMT) was developed through nonalloyed PdGe ohmic contact on an n+-GaAs cap layer. The lowest contact resistivity obtained was 1.2×10-7 Ω cm2 at 300°C. This allows us to change the sequence on the formation of source/drain and gate electrodes in the process of PHEMT fabrication, namely self-aligned gate PHEMT. Performance of the self-aligned gate PHEMT was remarkably pronounced with annealing temperature or the decrease of contact resistivity. This is due to the solid-phase regrowth of highly Ge-doped GaAs below the PdGe contact, which acts to reduce barrier height for electron tunneling.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)