High-Quality 1 eV In0.3Ga0.7As on GaAs Substrate by Metalorganic Chemical Vapor Deposition for Inverted Metamorphic Solar Cell Application

Abstract

In0.3Ga0.7As layers were grown by metalorganic chemical vapor deposition using step graded buffer layers on different misoriented GaAs(001) substrates. Smooth-surface In0.3Ga0.7As film with a root mean square roughness of 1.9 nm was obtained with the growth temperature of 490 °C using a 10-step graded parabolic-like indium profile buffer layer on the surface with the 6°-off cut toward the [111] direction. The threading dislocation density in the film was determined to be 1.2×106 cm-2 by transmission electron microscopy. The photoluminescence results obtained at 300 and 77 K indicate that very low recombination centers existed in the epilayer.