GaN-Rich Side of GaNAs Grown by Gas Source Molecular Beam Epitaxy

Abstract

A large variation in wavelength from the ultraviolet to longer than 2 µm could be achieved in the GaN-rich side of the GaN 1- x As x alloy due to the large bowing of bandgap energy. Layers of GaN 1- x As x are grown on (0001) sapphire substrates by electron cyclotron resonance molecular beam epitaxy (ECR-MBE) using an ion-removed ECR radical cell after the growth of GaN buffer layers. During the growth of GaN 1- x As x layers, a streaky reflection high-energy electron diffraction (RHEED) pattern was observed. The excitonic photoluminescence (PL) peak from the GaN-rich side of the GaN 1- x As x layer shows a large red shift as the As content changes. When an As content of up to x =0.009 is attained, a bandgap bowing parameter of 19.6 eV is experimentally obtained. Such a large value of the bowing parameter is promising for applications to optical devices operating over wide range of wavelength.