We have demonstrated a record short wavelength lasing at 244.63 nm with TE dominant polarization from GaN quantum wells (QWs) at room temperature (RT). The optical threshold of 310 kW/cm2 is comparable to state-of-the-art AlGaN QW lasers at similar wavelengths. The sample was grown on the AlN/sapphire template pesudomorphically. X-ray diffraction (XRD) shows unambiguous higher-order satellite peaks indicating a sharp interface amid the active region. The excitonic localization was revealed and studied by the photoluminescence (PL) and time-resolved PL (TRPL) spectroscopy at temperatures ranging from 15 K to RT. At 15 K, the multiple-component PL decay curves with the decay time varying from 62.6 to 2.77 ns at different energies confirmed the localized excitons. The peak energy of the temperature-dependent PL spectra exhibited the “S-shape” behavior; and the weak exciton localization with a small localization energy of 14.3 meV was observed. Therefore, even in the low temperature region, the escape possibility of excitons increased as the temperature rose. As a result, the fwhm of the emission spectra changed significantly when the temperature was below 150 K. Above 150 K, the PL decay shape changed from the two-component exponential decay to the single exponential decay, indicating complete delocalization of excitons. The work demonstrates the weak localization and thus smooth interface in the GaN/AlN active region, which are desirable for DUV lasers operating at RT.
Bibliographical noteKAUST Repository Item: Exported on 2021-04-21
Acknowledged KAUST grant number(s): BAS/1/1664-01-01, REP/1/3189-01-01, URF/1/3437-01-01, URF/1/3771-01-01
Acknowledgements: This work is supported by the National Key Research and Development Program of China (Grant No.2016YFB0400901), the Center of Micro-Fabrication and Characterization (CMFC) of WNLO, Chinese Academy of Sciences (Grant No. IIMDKFJJ-17-09), the National Natural Science Foundation of China (Grant Nos. 61704062, 61774065, and 61704176), the China Postdoctoral Science Foundation (Grant No. 2016M602287), and the Director Fund of WNLO. The KAUST authors appreciate the support of KAUST Baseline BAS/1/1664-01-01, GCC Research Council REP/1/3189-01-01, and Competitive Research Grants URF/1/3437-01-01 and URF/1/3771-01-01.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering