title: Deep and alignment free patterned etching of GaN surface using an atomic force microscope.
abstract: Successful deep and alignment-free patterned etching on GaN using atomic force microscope (AFM) local oxidation followed by in-situ chemical etching is demonstrated. Oxide ridges are grown on GaN on an AFM by applying positive sample bias at 80% humidity, with the oxidation reaction expedited by UV light. The oxide ridges are then etched by HCl solution, leaving troughs in the GaN surface. A dripping strategy for the in-situ chemical etching is recommended that allows deep, alignment-free multiple AFM oxidation/etching works on the GaN surface without any need of substrate removal from the AFM platform. Repeated etching followed by AFM oxidation on a spot on a GaN surface resulting in a hole as deep as 800 nm was also demonstrated. Further, a preliminary evaluation of the porosity of the AFM-grown oxide indicates that the oxide ridges grown on GaN at an AFM cantilever moving speed of 300 nm/s are porous in structure, with an estimated porosity of 86%, which porosity could be reduced if longer resident time of the AFM cantilever on the target oxidation region was used.
authors.affiliation: Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 202, Taiwan.
authors.forename: Jih-Shang
authors.initials: JS
authors.lastname: Hwang
authors.forename: Der-Chang
authors.initials: DC
authors.lastname: Chen
authors.forename: Li-Wei
authors.initials: LW
authors.lastname: Chen
authors.forename: Zhan-Shuo
authors.initials: ZS
authors.lastname: Hu
authors.forename: Zen-Yu
authors.initials: ZY
authors.lastname: You
authors.forename: Chih-Chiang
authors.initials: CC
authors.lastname: Wu
authors.forename: Tai-Yuan
authors.initials: TY
authors.lastname: Lin
authors.forename: Tsong-Ru
authors.initials: TR
authors.lastname: Tsai
authors.forename: Surojit
authors.initials: S
authors.lastname: Chattopadhyay