Anodic etching of GaN based film with a strong phase-separated InGaN/GaN layer: Mechanism and properties

作者：Gao, Qingxue; Liu, Rong; Xiao, Hongdi^*; Cao, Dezhong; Liu, Jianqiang; Ma, Jin

来源：Applied Surface Science, 2016, 387: 406-411.

DOI：10.1016/j.apsusc.2016.06.081

• Phase-separated InGaN/GaN layer
• MQW structure
• Nanopore
• Compressive stress relaxation

A strong phase-separated InGaN/GaN layer, which consists of multiple quantum wells (MQW) and super lattices (SL) layers and can produce a blue wavelength spectrum, has been grown on n-GaN thin film, and then fabricated into nanoporous structures by electrochemical etching method in oxalic acid. Scanning electron microscopy (SEM) technique reveals that the etching voltage of 8 V leads to a vertically aligned nanoporous structure, whereas the films etched at 15 V show branching pores within the n-GaN layer. Due to the low doping concentration of barriers (GaN layers) in the InGaN/GaN layer, we observed a record-low rate of etching (<100 nm/min) and nanopores which are mainly originated from the V-pits in the phase-separated layer. In addition, there exists a horizontal nanoporous structure at the interface between the phase-separated layer and the n-GaN layer, presumably resulting from the high transition of electrons between the barrier and the well (InGaN layer) at the interface. As compared to the as-grown MQW structure, the etched MQW structure exhibits a photoluminescence (PL) enhancement with a partial relaxation of compressive stress due to the increased light-extracting surface area and light-guiding effect. Such a compressive stress relaxation can be further confirmed by Raman spectra.

• 出版日期2016-11-30
• 单位山东体育学院; 山东大学