Fabrication of GaN hexagonal cones by inductively coupled plasma reactive ion etching

There is a growing demand for the patterning of gallium nitride for light extraction/absorption to improve the performance of photoelectric devices. In this paper, hexagonal cones were fabricated on Ga-polar GaN substrates using the inductively coupled plasma reactive ion etching method. It was found that the etch rate of different crystal faces could be altered by changing the ratio of BCl3 to Cl2 in the reactive gas mixture, which enabled hexagonal cone structures to be fabricated on the wurtzite GaN crystal. The mechanism of the GaN hexagonal cone formation was analyzed based on physical sputtering and chemical reaction, wherein the physical sputtering by heavy radicals assisted the bond breaking and the chemical erosion by Cl radicals that preferentially etched specific crystal planes. The hexagonal cones can be used on light-emitting diodes, photovoltaic devices, and for site control of quantum dots.