Wet chemical etching of AlN

Abstract

Single-crystal AlN grown on Al2O3 is found to be wet etched by AZ400K photoresist developer solution, in which the active component is KOH. The etching is thermally activated with an activation energy of 15.5±0.4 kcal mol−1, and the etch rate is found to be strongly dependent on the crystalline quality of the AlN. There was no dependence of etch rate on solution agitation or any crystallographic dependence noted, and the etching is selective over other binary group III nitrides (GaN, InN) and substrate materials such as Al2O3 and GaAs.

GaN nanostructuring for the fabrication of thin membranes and emerging applications

“…An airgap of the order of 1 µm was achieved with this technology, which is large enough to minimize interactions with the substrate and related light losses. The possibility of producing large airgaps is an advantage of dry RIE as compared to doping-selective and bandgapselective PEC etching and with different III-nitride sacrificial layers ensuring a limited airgap thickness of only a few hundreds of nanometers [55][56][57]. This issue is particularly critical for structures operating in the near infrared.…”

Photoelectrochemical Etching of InxGa1−xN

“…These films are degenerately ntype (~ 10 20 cm -3 ) due to residual defects or impurities. Ti metal contacts were patterned by liftoff on the periphery of the samples, and etching performed in a standard electrochemical cell consisting of a teflon sample holder and a Pt wire cathode [2][3][4][5][6][9][10][11][12][13][14]. An unfiltered 450W Hg arc lamp ~ 15cm from the sample provided illumination of the samples, which were immersed in unstirred KOH, NaOH or H 2 O/AZ400K solutions.…”

“…If the GaN nearsurface region has been damaged by processes such as dry etching or high temperature annealing, H 3 PO 4 , NaOH or KOH solutions have been found to remove the N 2 -deficient material and stop at the underlying undamaged GaN [5]. Both AlN [6,7] and InN [8] can be etched in hot alkaline solutions of NaOH or KOH, but there has been little success with the alloy InGaN [9].…”

Dry and Wet Etching for Group III – Nitrides

“…Conventional wet etching of GaN, AlN, and InN has been studied in base and acid solutions [39][40][41][42][43]. Earlier studies [39] conducted on low quality GaN produced etch rates as high as 1 µm/min.…”