GaN-rich side of GaNAs grown by gas source molecular beam epitaxy

A large variation in wavelength from the ultraviolet to longer than 2 mu m could be achieved in the GaN-rich side of the GaN1-xAsx alloy due to the large bowing of bandgap energy. Layers of GaN1-xAsx 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 GaN1-xAsx layers, a streaky reflection high-energy electron diffraction (RHEED) pattern was observed. The excitonic photoluminescence (PL) peak from the GaN-rich side of the GaN1-xAsx 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.