Atomic layer etching (ALE) of GaN on silicon substrates has been investigated using fluorine-based chemistry. The ALE process used for this study consists of a modification step using SF 6 plasma and a removal step using argon plasma. Two configurations were studied in which the distance between the sample and the plasma source was modified. The energy scan, synergy, selective etching of GaF x by Ar + ion bombardment, and self-limiting etching regime of the ALE of GaN were first investigated. An etch per cycle of 0.50 nm/cycle averaged over 100 cycles was reached for GaN ALE. The self-limiting regime was also obtained for both SF 6 and argon plasma steps. Moreover, a synergy rate as high as 78% was achieved. It was found that the GaF x -modified layer can be selectively sputtered by applying a self-bias voltage while the argon ion energy is maintained below the sputtering threshold of GaN.