Suppression of the kink effect in InGaAs/InAlAs HEMTs grown by MBEby optimizing the InAlAs buffer layer

摘要

The authors have examined the effects of InP substrate preparationand InAlAs growth temperature on the structural, electrical. and opticalproperties of In_0.52Al_0.48As layers grown on InPsubstrate. The substrate cleanliness affects the InAlAs growth modewhile the growth temperature determines the kinetics of growth. It isconcluded that the optimum InAlAs buffer layers have to be grown at T_G=530° C and the InP substrate has to be cleaned atT_t=530° C in order to obtain low defect density, smoothinterfaces, and high resistivity with minimum carrier trapping orcompensation centers. This optimization of the InAlAs buffer layer is ofcritical importance for the kink effect and, consequently, for theoutput conductance of the HEMTs (high electron mobility transistors) onInP. The optimized HEMT structures exhibited high transconductance, 530mS/mm for 1-μm gate length, low output conductance (19 mS/mm), andalmost elimination of the kink effect on the I-Vcharacteristics