Time-resolved photoluminescence spectral analysis of phonon-assisted DAP and e-A recombination in N+B-doped n-type 4H-SiC epilayers. (9th January 2019)

• Record Type: Journal Article
• Authors: Yang, Anli; Murata, Koichi; Miyazawa, Tetsuya; Tawara, Takeshi; Tsuchida, Hidekazu
• Is Part Of: Journal of physics. Volume 52:Number 10(2019)
• Publication Date: 2019-01-09
• Subjects: silicon carbide -- time-resolved photoluminescence -- donor-acceptor pair -- D center -- boron doping; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/aaf8e9
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: It is crucial to clarify the roles of phonon-assisted donor-acceptor pairs (DAPs) and free-to-acceptor (e-A) emissions in n -type 4H-SiC doped with nitrogen (N) and boron (B), where N and B induce the shallow donor and the D center (deep B) acceptor levels, respectively, in order to understand the complicated carrier recombination mechanism, as well as developing fluorescent SiC with a high color rendering index by controlling the ratio of the two overlapped emissions. Here, time-resolved photoluminescence (TRPL) spectral analyses were performed, in which phonon-assisted DAPs and e-A components were individually recognized. The D center-related green luminescence (1.6–2.8 eV) shows a non-exponential decay followed by a very slow decay in TRPL measurements at room temperature (RT). It emerges that most of the DAP emission intensities decay much faster than e-A emissions and contribute to what is initially fast and non-exponential decay at low temperatures, while the slow decay at RT is mainly from e-A emissions. At a much higher temperature, such as 473 K, only the e-A emission remains and the decay transforms from non-exponential to exponential behavior. High-temperature thermal quenching of e-A emissions exhibits different behaviors for samples with differing B doping concentrations. An activation energy of 0.6 eV was estimated from the Arrhenius plot of e-A emission intensity from a B-doped sample, which matches the D center level. This indicates that the hole thermal emission rate is greatly enhanced at a high temperature, which accelerates the decay of e-A emission intensity at high temperatures.