Molecular beam epitaxy of highly mismatched N-rich GaN_1-xSb_x and InN_1-xAs_x alloys

GaN materials alloyed with group V anions form the so-called highly mismatched alloys (HMAs). Recently, the authors succeeded in growing N-rich GaN_1-xAs_x and GaN_1-xBi_x alloys over a large composition range by plasma-assisted molecular beam epitaxy (PA-MBE). Here, they present first results on PA-MBE growth and properties of N-rich GaN_1-xSb_x and InN_1-xAs_x alloys and compare these with GaN_1-xAs_x and GaN_1-xBi_x alloys. The enhanced incorporation of As and Sb was achieved by growing the layers at extremely low growth temperatures. Although layers become amorphous for high As, Sb, and Bi content, optical absorption measurements show a progressive shift of the optical absorption edge to lower energy. The large band gap range and controllable conduction and valence band positions of these HMAs make them promising materials for efficient solar energy conversion devices. © 2013 American Vacuum Society.