Ohmic Contact Properties of Photo-Chemically Etched Nonpolar A-Plane (112¯0) GaN Films. (1st January 2017)

• Record Type: Journal Article
• Authors: Baik, Kwang Hyeon; Lee, Sohyun; Jang, Soohwan
• Is Part Of: ECS journal of solid state science and technology. Volume 6:Number 11(2017)
• Page Start: S3001
• Page End: S3004
• Publication Date: 2017-01-01
• Subjects: a-plane -- etching -- GaN -- nonpolar -- Ohmic -- photo-chemical; Solid state chemistry -- Periodicals; Electronics -- Materials -- Periodicals; Electrochemistry -- Periodicals; 541.0421
• DOI: 10.1149/2.0011711jss
• Languages: English
• ISSNs: 2162-8777

Abstract

Abstract : Nonpolar a- plane ( 11 2 ¯ 0 ) GaN ( a- GaN) was photo-chemically etched under ultraviolet illumination using alkali KOH solution, and the Ohmic contact properties on the etched a- GaN epitaxial layer were investigated. After photo-chemical etching, the striated surface morphology along the c- axis [0001] direction was obtained having triangular prisms consisting of m -plane { 10 1 ¯ 0 } facets. The properties of Ti/Al/Ni/Au Ohmic contact on surface-textured a -GaN films were studied with transmission line method patterns aligned along the specific crystal orientations. The minimum specific contact resistance of 9.97 × 10 −5 Ω·cm 2 was achieved along the c- axis on the etched GaN surface at the annealing temperature of 750°C. The etched a- GaN showed higher electrical conductivity along the c- axis than along m- axis. This anisotropic behavior is in contrast to that of the unetched a- GaN where carrier scattering by basal plane stacking faults in the direction perpendicular to the c- axis is a major factor in determining opposite anisotropic conductivity. The higher conductivity along the c-axis of the etched a -GaN film could be explained by more dominant effect of surface roughness scattering.