 We demonstrate a new substrate cleaning and buffer growth scheme in beta GA-203 epitaxial thin films. Using metal organic vapor phase epitaxy MOVP, we show the potential of designing C-doped beta GA-203 channels with exceptional transport properties. These channels show record high electron mobility in the range of 196 to 85 cm2 slash vs. This article was authored by Arkabatacharya, Carl Peterson, Takiki Ito, and others.