Fabrication and improved photoelectrochemical properties of a transferred GaN-based thin film with InGaN/GaN layers. Issue 32 (2nd August 2017) - Cao, Dezhong
Abstract : The mesoporous GaN-based thin films were transferred onto quartz and n-Si substrates. Compared to the film on quartz substrate, the film on n-Si substrate exhibited better photoelectrochemical performance. Abstract : Herein, a lift-off mesoporous GaN-based thin film, which consisted of a strong phase-separated InGaN/GaN layer and an n-GaN layer, was fabricated via an electrochemical etching method in a hydrofluoric acid (HF) solution for the first time and then transferred onto quartz or n-Si substrates, acting as photoanodes during photoelectrochemical (PEC) water splitting in a 1 M NaCl aqueous solution. Compared to the as-grown GaN-based film, the transferred GaN-based thin films possess higher and blue-shifted light emission, presumably resulting from an increase in the surface area and stress relaxation in the InGaN/GaN layer embedded on the mesoporous n-GaN. The properties such as (i) high photoconversion efficiency, (ii) low turn-on voltage (−0.79 V versus Ag/AgCl), and (iii) outstanding stability enable the transferred films to have excellent PEC water splitting ability. Furthermore, as compared to the film transferred onto the quartz substrate, the film transferred onto the n-Si substrate exhibits higher photoconversion efficiency (2.99% at −0.10 V) due to holes (h + ) in the mesoporous n-GaN layer that originate from the n-Si substrate.