Gas Source Molecular Beam Epitaxial Growth of GaN_1-xP_x (x \Leq 0.015) Using Ion-Removed Electron Cyclotron Resonance Radical Cell

Abstract

The GaN-rich side of GaN 1- x P x alloy exhibits a potentially large variation in band-gap energy with P content due to its large bowing. GaN 1- x P x layers 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 high-quality GaN layers. During the growth of the high-quality GaN layers, ×2 reflection high-energy electron diffraction (RHEED) patterns are observed. During the growth of the GaN 1- x P x layers, RHEED pattern exhibits a ×1 streak. The near band edge excitonic photoluminescence (PL) peak from the GaN-rich side of the GaN 1- x P x layers shows a large red shift with change in P content. A P content of as large as x =0.015 is obtained. However, at x =0.015 phase separation into GaN-rich GaN 1- x P x and GaP-rich GaP 1- y N y is observed.