Changing oblique angles of pyramid facets fabricated by wet etching of N polar GaN

Abstract

Wet etching was performed on N polar GaN, which was fabricated by laser lift-off from a sapphire substrate. Dodecagonal pyramids appeared on the N-polar GaN surface after immersion into hot H 3 PO 4 solution even if it had been etched previously with hot KOH solution. According to the symmetry of the space group of C 6v 4 -P 6 mc, the oblique angle and crystallographic plane indices of the pyramid facets were obtained. It was observed that the oblique angles of the etched facets decreased from the tip to the base of the pyramids. The etching rate was fast when the etching temperature was above 130 uC, and the oblique angle at the base was reduced. The enhancement of light output with increasing etching temperature has been confirmed. The polarization charges on the different facets were assigned to a kinetics-limited process by the special behavior of the hot H 3 PO 4 etching.

GaN nanowire arrays with nonpolar sidewalls for vertically integrated field-effect transistors

“…The apparent semipolar facets and nonpolar facets are regarded chemically stable with low etch rates since they form a concave structure [19]. This is in agreement with the results reported for stable semipolar facets (e.g., {1011 ¯¯} or {1022 ¯¯}) formed during chemical etching on N-polar GaN surfaces [20]. (iv) Hexagonal shape.…”

Fabrication of Pyramid Structure Substrate Utilized for Epitaxial Growth Free-Standing GaN

“…The plasma-assisted molecular beam epitaxy (MBE)-grown GaN was etched, and there were some hexagonal pyramids with six facets formed in the N-polar face. The lift-off freestanding GaN was etched by hot phosphoric acids, and dodecagonal pyramids could be obtained [22,23]. However, pyramid structures formed in the N-polar face of the MOCVD-GaN have not been investigated.…”