Fabrication of 250-nm T-gate In52Al48As-In70Ga30As pHEMT using a novel solvent reflow technique at room temperature

An In₅₂Al₄₈As-In₇₀Ga₃₀As pHEMT with 250-nm T-Gate structure has been successfully fabricated by utilising a conventional 1μm i-Line lithography and a novel solvent reflow technique. The key advantage of this process is its capability of fabricating nano-scaled structures by using optical lithography with high throughput at very low temperature. The large gate shrinkage (>;0.70μm) from the original 1-μm foot print by solvent reflow, coupled with the fabrication of mushroom gate structures, yields a very high performance 250-nm T-gate device. For a 2×50μm device and with a 3μm drain-source distance, the maximum GM and IDS are 940mS/mm and 580mA/mm respectively and its associated cut-off frequency is 90 GHz.