Dislocation density in GaN determined by photoelectrochemical and hot-wet etching

Visconti, P.; Jones, K. M.; Reshchikov, M. A.; Cingolani, R.; Morkoc¸, H.; Molnar, R. J.
November 2000
Applied Physics Letters;11/27/2000, Vol. 77 Issue 22
Academic Journal
Defects in GaN layers grown by hydride vapor-phase epitaxy have been investigated by photoelectrochemical (PEC) etching, and by wet etching in hot H[sub 3]PO[sub 4] acid and molten potassium hydroxide (KOH). Threading vertical wires (i.e., whiskers) and hexagonal-shaped etch pits are formed on the etched sample surfaces by PEC and wet etching, respectively. Using atomic-force microscopy, we find the density of "whisker-like" features to be 2x10[sup 9] cm[sup -2], the same value found for the etch-pit density on samples etched with both H[sub 3]PO[sub 4] and molten KOH. This value is comparable to the dislocation density obtained in similar samples with tunneling electron microscopy, and is also consistent with the results of Youtsey and co-workers [Appl. Phys. Lett. 73, 797 (1998); 74, 3537 (1999)]. © 2000 American Institute of Physics.


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