Vapor-phase epitaxial lateral overgrowth of ZnSe on GaAs

We describe and demonstrate a process for ZnSe epitaxial lateral overgrowth (ELOG) on stripe-patterned, oxide-masked (1 1 1)GaAs substrates using a si mple near-equilibrium chemical Vapor transport process based on a reversibl e reaction mediated by hydrogen at atmospheric pressure. The ELOG process e xhibits excellent selectivity, wherein epitaxial seeding and initial growth is restricted to mask openings, and subsequent lateral epitaxy has aspect ratios as high as 20. We also achieved near-seamless impinging growth of co ntinuous epilayers of ZnSe on the masked substrate. Etch-pit density studie s indicate defect reduction in areas of the ZnSe overgrown atop the oxide c ompared to areas of the ZnSe epilayer seeded directly over the mask opening s. The composite GaAs substrate, oxide mask, and ZnSe epilayer structure is under considerable stress due to the thermal expansion mismatch of these m aterials. Some approaches for reducing thermal stress are discussed. (C) 20 00 Elsevier Science B.V. All rights reserved.