An In(0.15)Ga(0.85)As/GaAs pseudomorphic single quantum well HEMT

This letter describes high electron mobility transistors (HEMTs) utilizing a conducting channel which is a single In(0.15)Ga(0.85)As quantum well grown pseudomorphically on a GaAs substrate. A Hall mobility of 40,000 sq cm/V s has been observed at 77 K. Shubnikov-de Haas oscillations have been observed at 4.2 K which verify the existence of a two-dimensional electron gas at the In(0.15)Ga(0.85)As/GaAs interface. HEMTs fabricated with 2-micron gate lengths show an extrinsic transconductance of 90 and 140 mS/mm at 300 and 77 K, respectively - significantly larger than that previously reported for strained-layer superlattice In(x)Ga(1-x)As structures which are nonpseudomorphic to GaAs substrates. HEMTs with 1-micron gate lengths have been fabricated, which show an extrinsic transconductance of 175 mS/mm at 300 K which is higher than previously reported values for both strained and unstrained In(x)Ga(1-x)As FETs. The absence of Al(x)Ga(1-x)As in these structures has eliminated both the persistent photoconductivity effect and drain current collapse at 77 K.