Effect of growth temperature of GaAsx Sb1-x metamorphic buffer layer on electron mobility of InAs/AlSb heterostructures grown on Si substrate

Abstract

The InAs/AlSb heterostructures with step-graded GaAsxSb1-x metamorphic buffer layers grown on Si substrates by molecular beam epitaxy are studied. The step-graded GaAsxSb1-x metamorphic buffer layers are used to relax the strain and block defects at each interface of the layers. Meanwhile, adding Sb to GaAs is also beneficial to suppressing the formation of dislocations in the subsequent materials. The influences of the growth temperature of the step-graded GaAsxSb1-x metamorphic buffer layer on the electron mobility and surface topography are investigated for a series of samples. Based on the atomic force microscopy (AFM), high resolution x-ray diffraction (HRXRD), reciprocal space map (RSM), and Hall measurements, the crystal quality and composition of GaAsxSb1-x layer are seen to strongly depend on growth temperature while keeping the Ga growth rate and V/III ratio constant. The results show that the highest electron mobility is 10270 cm2/V•s and the roughness is 4.3 nm for the step-graded GaAsxSb1-x metamorphic buffer layer grown at a temperature of 410 °C.