Gas source MBE growth of GaN rich side of GaN1-xPx using ion-removed ECR radical cell

GaN-rich side of GaN1-xPx alloy are grown on (0 0 0 1) 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. GaN1-xPx exhibits potentially large variation of band-gap energy with P composition due to its large bowing. Maximum P composition of x = 0.015 is obtained. However, at the growth condition of high PH3 flow rate, phase separation into GaN-rich GaN1-xPx and GaP-rich GaP1-yNy is observed. Near band edge excitonic photoluminescence (PL) peak from GaN-rich side of GaN1-xPx layers shows large red shift with P composition. It suggests that the direct band edge of GaNP alloy shows large bowing.