Liquid phase epitaxial growth and characterization of InAsxSb1−;x AND In1−yGaySb ON (111)B InSb substrates

Abstract

Liquid phase epitaxial growth of InAsxSb1−x, for 0<x<0.27 and In1−yGaySb, for 0<y<0.37, has been successfully accomplished on (111)B InSb substrates between the temperatures of 450 and 520°C. The phase diagrams and the growth conditions for high-quality planar epitaxial layers have been determined. For growth of InAsxSb1−x for high values of x, the strong tendency of the ternary melt to dissolve the substrate, even when the liquid is a few degrees below its melting point, was negated by using large supercooling. Small supercooling of zero to 5.6°C were required over the whole range of composition examined for (In.Ga)Sb, whereas, for example, supercooling greater than 30°C was required to grow InAso.26Sbo.74 to avoid substrate dissolution. Lattice mismatch to the substrate was relieved by compositional grading. Etch pit studies in both materials yielded dislocation densities ranging from 5.8 × 102 to 2×106 cm−2 with most materials in the low 104 range. Hall and resistivity measurements performed at 300K and 77K on most samples showed an impurity contamination of the epitaxial layers. Some samples were n-type (carrier concentration approximately 1017/cm3), with varying degrees of acceptor compensation and others were n-type (carrier concentration approximately l017/cm3) at room temperature due to intrinsic conduction, but exhibited p-type conduction (carrier concentration approximately 5×l0l6/cm3) at 77K. Hall measurements performed on one of the latter samples ofvery low As content from 77K to 4.2K to examine hole freeze-out yielded an acceptor level ionization energy of 0.0126eV which is close to the effective mass acceptor level ionization energy in InSb. The electron-to-hole mobility ratio was also found to be 65.9. Electron microprobe analysis showed silicon to be the dominant impurity.