Influence of growth conditions on mobility and anisotropy of In/sub y/Ga/sub 1-y/As/In/sub 0.52/Al/sub 0.48/As/InP HEMTs with y=0.53 to 0.80

We have studied the mobility behaviour of HEMT structures with lattice matched and strained channels as a function of channel growth temperature and thickness. Decreasing the channel growth temperature leads to mobility reduction and anisotropy in the lattice matched system. The pseudomorphic channel shows superior mobility in the [1-10] direction compared to the [110] direction under all growth conditions, Growth at lower temperatures prevents strain relaxation and can considerably improve the mobility of pseudomorphic HEMT structures. We have measured mobilities of 14300 and 14900 cm/sup 2//Vs at electron densities of 3.1 and 2.6/spl times/10/sup 12/ cm/sup -2/ for structures with strained channels.