Scaling up antimonide wafer production: innovation and challenges for epitaxy ready GaSb and InSb substrates

In this paper we describe the growth and characterization of antimonide based compound semiconductor substrates. The Czochralski technique has been used to grow single crystals of 4" InSb and 4" GaSb with dislocation densities of <20/cm2 and <100/cm2, respectively. Epitaxy ready wafer surfaces have been characterized by surface microscopy and spectroscopic ellipsometry, revealing sub-nanometer levels of surface roughness (rms) and oxide coverage in the 10-50 Angstrom range. GaSb wafers with thinner oxides (<20 Angstroms) have been developed and quality assessments made by epitaxial growth testing. Surface morphology evaluations indicate high levels of surface quality, comparable to pretreated variants of the same substrate type. We also illustrate current crystal growth systems and ingot forms, and discuss the challenges associated with scaling present InSb and GaSb technologies to deliver larger substrate formats.