Gas source molecular beam epitaxial growth of GaN1-xPx (x<=0.015) using ion-removed electron cyclotron resonance radical cell

The GaN-rich side of GaN1-xPx alloy exhibits a potentially large variation in band-gap energy with P content due to its large bowing. GaN1-xPx 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, x2 reflection high-energy electron diffraction (RHEED) patterns are observed. During the growth of the GaN1-xPx layers, RHEED pattern exhibits a x1 streak. The near band edge excitonic photoluminescence (PL) peak from the GaN-rich side of the GaN1-xPx 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 GaN1-xPx and GaP-rich GaP1-yNy is observed.