New directions in GaN material research: Thinner and smaller

As the GaN material research is reaching maturity with the phenomenal success in LED industry, there is now need to look beyond conventional epitaxy. In this paper we will summarize a few novel directions that we are pursuing. In the first part of this paper, we highlighted our effort to grow single crystal GaN on amorphous substrate. With the successive applications of a phenomenon called evolutionary selection along two perpendicular axes, we remove the degree of freedom in grain orientations from 3 to 0 and successfully prepared single-crystalline GaN on amorphous oxide template. We dedicated the second part of this paper to our recent findings in GaN nanomembrane. Via conductivity selective electrochemical etching, we have fabricated GaN nanomembrane as thin as 90 nm. The thin and "softa" GaN nanomembrane is proven to maintain its as-grown crystal quality. We have also demonstrated a 300 nm thick InGaN/GaN nanomembrane LED.