Indium and impurity incorporation in InGaN films on polar, nonpolar, and semipolar GaN orientations grown by ammonia molecular beam epitaxy

The effects of NH3 flow, group III flux, and substrate growth temperature on indium incorporation and surface morphology have been investigated for bulk InGaN films grown by ammonia molecular beam epitaxy. The incorporation of unintentional impurity elements (H, C, O) in InGaN films was studied as a function of growth temperature for growth on polar (0001) GaN on sapphire templates, nonpolar (10 (1) over bar0) bulk GaN, and semipolar (11 (2) over bar2), (20 (2) over bar1) bulk GaN substrates. Enhanced indium incorporation was observed on both (10 (1) over bar0) and (20 (2) over bar1) surfaces relative to c-plane, while reduced indium incorporation was observed on (11 (2) over bar2) for co-loaded conditions. Indium incorporation was observed to increase with decreasing growth temperature for all planes, while being relatively unaffected by the group III flux rates for a 1:1 Ga:In ratio. Indium incorporation was found to increase at the expense of a decreased growth rate for higher ammonia flows; however, smooth surface morphology was consistently observed for growth on semipolar orientations. Increased concentrations of oxygen and hydrogen were observed on semipolar and nonpolar orientations with a clear trend of increased hydrogen incorporation with indium content. (C) 2012 American Vacuum Society. [http://dx.doi.org/10.1116/1.4727967]