Fabrication of strained and double heterojunction In/sub x/Ga/sub 1-x/P/In/sub 0.2/Ga/sub 0.8/As high electron mobility transistors grown by solid-source molecular beam epitaxy

Double heterojunction (DH) In/sub 0.48/Ga/sub 0.52/P/In/sub 0.20/Ga/sub 0.80/As and strained single heterojunction (SSH) In/sub 0.40/Ga/sub 0.60/P/In/sub 0.20/Ga/sub 0.80/As/GaAs high electron mobility transistor (HEMT) structures were grown by solid-source molecular beam epitaxy (SSMBE) using a valved phosphorus cracker cell. The DC and RF performance of the SSH-HEMT and DH-HEMT were compared with the single heterojunction (SH) HEMT. The results show a significant improvement in device characteristics in the SSH-HEMT with In/sub 0.40/Ga/sub 0.60/P spacer and Schottky layer, due to better carrier confinement in the channel. The SSH-HEMT with 0.35-/spl mu/m gate length exhibits a peak transconductance (G/sub m/) of 470 mS/mm, maximum drain current (I/sub DSmax/) of 550 mA/mm, and current gain cut-off frequency (f/sub T/) of 50 GHz. These values are approximately 7%, 10% and 25% higher than the respective values for a DH-HEMT of identical gate length.