Wet chemical etching of AlN and InAlN in KOH solutions

Journal Article · Fri Nov 01 04:00:00 EST 1996 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1837271· OSTI ID:428172

Vartuli, C B; Pearton, S J; Lee, J W; Abernathy, C R; Mackenzie, J D ^[1]; Zolper, J C; Shul, R J ^[2]; Ren, F ^[3]

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1. Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering
2. Sandia National Labs., Albuquerque, NM (United States)
3. Bell Labs., Murray Hill, NJ (United States). Lucent Technologies

Wet chemical etching of AlN and In{sub x}Al{sub 1{minus}x}N was investigated in KOH-based solutions as a function of etch temperature and material quality. The etch rates for both materials increased with increasing etch temperatures, which was varied from 20 to 80 C. The crystal quality of AlN prepared by reactive sputtering was improved by rapid thermal annealing at temperatures to 1,100 C, with a decreased wet etch rate of the material measured with increasing anneal temperature. The etch rate decreased approximately an order of magnitude at 80 C etch temperature after an 1,100 C anneal. The etch rate for In{sub 0.19}Al{sub 0.81}N grown by metallorganic molecular beam epitaxy was approximately three times higher for material on Si than on GaAs. This corresponds to the superior crystalline quality of the material grown on GaAs. Etching of In{sub x}Al{sub 1{minus}x}N was also examined as a function of In composition. The etch rate initially increased as the In composition changed from 0 to 36%, and then decreased to 0 {angstrom}min for InN. The authors also compared the effect of doping concentration on etch rate. Two InAlN samples of similar crystal quality were also etched; one was fully depleted with n < 10{sup 16} cm{sup {minus}3} (2.6% In) and the other n {approximately} 5 {times} 10{sup 18} cm{sup {minus}3} (3.1% In). At low etch temperature, the rates were similar, but above 60 C the n-type sample etched faster, approximately three times faster at 80 C. The activation energy for these etches is very low, 2.0 {+-} 0.5 kcal/mol for the sputtered AlN. The activation energies for InAlN were dependent on In composition and were in the range 2 to 6 kcal/mol. GaN and InN layers did not show any etching in KOH at temperatures up to 80 C.

• Research Organization: Sandia National Laboratory
• Sponsoring Organization: National Science Foundation, Washington, DC (United States); Sandia National Labs., Albuquerque, NM (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 428172
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 11 Vol. 143; ISSN 0013-4651; ISSN JESOAN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
CHEMICAL REACTION KINETICS
CRYSTAL STRUCTURE
ETCHING
INDIUM NITRIDES
POTASSIUM HYDROXIDES
TEMPERATURE DEPENDENCE