Optimisation of GaN overgrowth of InAlN for DBRs

Abstract

AbstractThe growth of InAlN lattice matched to GaN is a recent development with a major application in nitride distributed Bragg reflectors (DBRs). In this work we investigate three ways of capping lattice matched InAlN layers to make the GaN layers in a DBR, while ensuring that InAlN is not damaged in the process and that the top GaN surface is suitable for further growth. Growing the GaN caps in a nitrogen atmosphere at the same temperature as the InAlN does not observably affect the InAlN epilayer but the cap has a top surface with large undulations unsuitable for DBRs. Growing the GaN at 1000 °C in a hydrogen atmosphere results in good GaN surfaces without altering the bulk of the InAlN epilayer but does alter the InAlN surface, possibly by causing the desorption of In. The advantages of both methods can be combined by growing the first 10 nm of the cap at the same temperature as the InAlN and the rest at 1000 °C. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)