The initial stages of growth of CuPtB ordered Ga0.52In0.48P/GaAs and Ga0.47In0.53As/InP

Abstract

Atomic force microscopy and Raman spectroscopy were used to investigate the development of the surface morphology and ordering of Ga0.52In0.48P and Ga0.47In0.53As. A series of lattice-matched highly ordered Ga0.52In0.48P/GaAs and Ga0.47In0.53As/InP samples ranging in thickness from 2 to 50 nm were grown by low-pressure metalorganic vapor phase epitaxy on (001) direct and vicinal substrates. Raman spectroscopy provided direct evidence of CuPtB-type ordering in layers as thin as 10 nm for Ga0.52In0.48P and 5 nm for Ga0.47In0.53As. We find that the morphology of both Ga0.52In0.48P and Ga0.47In0.53As on (001)6B substrates consists of ridges with heights ranging from 2 to 10 nm, which are aligned predominately along the [110] direction. For Ga0.52In0.48P growth on (001) direct substrates, ridges similar to those obtained on 6B vicinal substrates form with no preferential orientation, while Ga0.47In0.53As growth on (001) direct substrates proceeds by a combination of two-dimensional-island and step-flow growth. The average roughness of the GaInP layers is approximately twice that of GaInAs layers. These findings suggest it may be difficult to produce abrupt large-area heterointerfaces in structures containing ordered Ga0.52In0.48P and Ga0.47In0.53As alloys.