Precise Structural Control of GaN Porous Nanostructures Utilizing Anisotropic Electrochemical and Chemical Etching for the Optical and Photoelectrochemical Applications. Issue 7 (1st January 2017)

• Record Type: Journal Article
• Authors: Kumazaki, Yusuke; Matsumoto, Satoru; Sato, Taketomo
• Is Part Of: Journal of the Electrochemical Society. Volume 164:Issue 7(2017)
• Page Start: H477
• Page End: H483
• Publication Date: 2017-01-01
• Subjects: anisotropic etching -- electrochemical etching -- GaN -- nano structure -- photocatalyst -- photoelectrode -- porous structure -- tetramethylammonium hydroxide (TMAH) -- water splitting; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0771707jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : A low-damaged wet process utilizing electrochemical (EC) etching and subsequent chemical etching has been developed for the fabrication of GaN porous structures. Superior controllability in depth and diameter could be obtained by achieving anisotropic nature of the vertical direction to the substrate by EC etching and horizontal direction by tetramethylammonium hydroxide (TMAH) etching, respectively. The optical and photoelectrochemical properties of GaN porous structures were very sensitive to the structural properties. Photoreflectance measurement revealed that porous sample had an effective refractive index that could be controlled by TMAH etching time. In photoelectrochemical measurement, the incident-photon-to-current conversion efficiency (IPCE) was dramatically enhanced to as high as 91% by the formation of porous structures. A series of experimental results were consistently explained by the change of thickness of pore wall and width of space charge region.