Dislocation- and crystallographic-dependent photoelectrochemical wet etching of gallium nitride

Polarity and dislocation dependence study of photoelectrochemical wet etching on GaN was carried out on lateral epitaxial overgrown nonpolar (1120)a-GaN/(1102)r-plane sapphire substrate. This LEO nonpolar GaN sample has low dislocation density Ga- and N-faces exposed horizontally in opposite directions, which can be exposed to identical etching conditions for both polarity and dislocation dependence study. It is observed that N-face GaN is essentially much chemically active than Ga-face GaN, which shows the hexagonal pyramids with {1011} facets on the etched N face. No obvious etching was observed on Ga face in the same etch condition. As for dislocation dependence, the “wing” (low dislocation density) region was etched faster than the “window” (high dislocation density) region. Smooth etched surfaces were formed with the (1122) facet as an etch stop plane both on Ga and N-wing region.

[1]  S. Denbaars,et al.  Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening , 2004 .

[2]  L. Coldren,et al.  Chemical mechanical polishing of gallium nitride , 2002 .

[3]  L. Coldren,et al.  Development of selective lateral photoelectrochemical etching of InGaN/GaN for lift-off applications , 2001 .

[4]  James S. Speck,et al.  STRUCTURAL ORIGIN OF V-DEFECTS AND CORRELATION WITH LOCALIZED EXCITONIC CENTERS IN INGAN/GAN MULTIPLE QUANTUM WELLS , 1998 .

[5]  AlGaN/GaN current aperture vertical electron transistors fabricated by photoelectrochemical wet etching , 2003 .

[6]  Nils Guenter Weimann,et al.  GaN nanotip pyramids formed by anisotropic etching , 2003 .

[7]  Noel C. MacDonald,et al.  Photoelectrochemical undercut etching for fabrication of GaN microelectromechanical systems , 2001 .

[8]  Ilesanmi Adesida,et al.  Rapid evaluation of dislocation densities in n-type GaN films using photoenhanced wet etching , 1999 .

[9]  Ilesanmi Adesida,et al.  Dopant-selective photoenhanced wet etching of GaN , 1998 .

[10]  James S. Speck,et al.  Polarity determination of a-plane GaN on r-plane sapphire and its effects on lateral overgrowth and heteroepitaxy , 2003 .

[11]  S. Denbaars,et al.  Threading dislocation reduction via laterally overgrown nonpolar (112̄0)a-plane GaN , 2002 .

[12]  I. Adesida,et al.  Gallium nitride whiskers formed by selective photoenhanced wet etching of dislocations , 1998 .

[13]  James S. Speck,et al.  Structural characterization of nonpolar (112̄0) a-plane GaN thin films grown on (11̄02) r-plane sapphire , 2002 .

[14]  S. Denbaars,et al.  Backside-illuminated photoelectrochemical etching for the fabrication of deeply undercut GaN structures , 2000 .