Thursday, 6 April 2017

GaN with Laterally Aligned Nanopores To Enhance the Water Splitting

Source: J. Phys. Chem. C, Article ASAP; DOI: 10.1021/acs.jpcc.7b00748; Publication Date (Web): March 9, 2017; Copyright © 2017 American Chemical Society

Authors

Chao Yang†‡, Lei Liu†‡ , Shichao Zhu†‡, Zhiguo Yu†, Xin Xi†‡, Shaoteng Wu†‡, Haicheng Cao†‡, Jinmin Li†‡, and Lixia Zhao*†‡

† Semiconductor Lighting Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, No. A35, Qinghua East Road, Haidian District, Beijing 100083, China
‡ College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Shijingshan District, Beijing 100049, China
*E-mail: lxzhao@semi.ac.cn. Tel: +86-10-82305476.

Abstract

GaN with aligned nanopores was fabricated using a lateral anodic etching process in HNO3 solution. This laterally porous structure can be modified from triangular pores to quasi-circular pores with increasing the voltage, indicating the transformation from anisotropic etching gradually toward isotropic etching. Furthermore, we have established the correlation between the etching current and pore trajectories based on the in situ chronoamperometry and find that the lateral etching is initially driven by the avalanche effect, then enter a steady state as a balance between the oxidation and dissolution of GaN at the pore tips. The water splitting properties of the laterally porous photoanode have also been studied. Compared with the as-grown GaN film, nearly 3.4 times enhancement of self-driven photocurrent was achieved for the porous GaN with triangular pores. Our findings not only reveal the formation kinetics of porous GaN but also pave a way for the application of solar water splitting using laterally porous GaN.