youtsey-mrssp-468-349

Data for reference youtsey-mrssp-468-349

Photoelectrochemical Etching of GaN

C. Youtsey, G. Bulman, I. Adesida

Materials Research Society Symposium Proceedings 468, 349 (1997).

Below is the abstract submitted to the meeting, not the abstract of the published paper:
The need for effective processing methods for device fabrication in the GaN material system has grown, as high quality epitaxial layers have recently become available. The wide bandgap and high chemical stability of GaN make it an excellent candidate for high temperature/high power devices and short wavelength emitters and detectors. While conventional dry etching techniques have been successfully applied towards etching of the group-III nitrides, very few wet etchants have been identified, a consequence of the unusual chemical inertness of the nitrides. Room temperature etching of AlN has been reported using AZ200K developer, while InN films may be etched in aqueous KOH and NaOH at elevated temperatures. GaN has been found to etch only very slowly (∼2 nm/min) in NH₄OH solutions. Since dry etching processes possess a number of significant drawbacks compared to wet etching techniques (such as the formation of ion-induced damage, difficulty in etching layers selectively, and relative complexity), it is important to explore alternative patterning methods. Photochemical (PEC) etching of GaN has recently been demonstrated by Minsky et al. using KOH solution and HeCd laser illumination (325 nm). Wet PEC etching has been explored for a variety of semiconductor materials and shown to produce high etch rates, good anisotropy, as well as high selectivity between materials of different doping and bandgap. In this work we report on the use of broad-area Hg lamp illumination to achieve PEC etching of GaN and AlGaN materials. Results will be presented for different doping types and their application towards achieving dopant selective etchings of heterostructure layers. Additionally, the significance of material defects on and their influence on the etched surface morphology will be discussed.

This paper is part of Gallium Nitride and Related Materials II

Contributed by Materials Research Society

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