A room-temperature photoelectrochemical wet etching process is describ
ed that produces smoothly etched GaN surfaces using KOH solution and H
g are lamp illumination. Atomic force microscope measurements indicate
a root-mean-square etched surface roughness of 1.5 nm, which compares
favorably to the unetched surface roughness of approximately 0.3 nm.
Etch rates of 50 nm/min were obtained using a KOH solution concentrati
on of 0.02 M and an illumination intensity of 30 mW/cm(2). It is shown
that the smooth etching occurs under conditions of low KOH solution c
oncentration and high light intensities, which result in a diffusion-l
imited etch process. (C) 1998 American Institute of Physics.