Fine Photoluminescence Spectroscopic Characterization of Interfacial Effects on Emission Properties of InGaN/GaN Multiple Quantum Wells in a Blue-Light Laser Diode Structure

Journal Article (Journal Article)

In growing InGaN/GaN multiple quantum wells (MQWs) with the technique of metal-organic chemical vapor deposition (MOCVD), the introduction of an appropriate amount of H2 into the N2 carrier gas for the growth of the GaN barrier layers can effectively improve the crystalline quality of the well/barrier interface and therefore enhance the luminescence efficiency of the quantum wells. In this work, we carried out detailed photoluminescence (PL) spectroscopic measurements on the luminescence properties of InGaN/GaN MQWs in the device structure for blue-light laser diodes, and the effects of H2 in the carrier gas for GaN barrier growth on the MQWs, including the improved interface quality, the enhanced luminescence and the underlying mechanisms, have been investigated. The PL spectra of the InGaN/GaN MQWs acquired at room temperature reveal that the introduction of 2.5% H2 in the N2 carrier gas leads to increased emission efficiency by 75%, blue-shifted peak energy by 17 meV, and narrowed full width at half maximum (FWHM) by 10 meV. With the PL spectra measured at varied excitation powers, the quantum-confined Stark effect (QCSE) and band-filling effect on the emission performance of the MQWs have been distinguished, and the QCSE effect is found to dominantly determine the emission energy and width, which can be effectively reduced by the introduction of H2. Upon the complete screening of the QCSE effect, the peak energy of the MQWs emission is located at 2.75 eV. The dependence of the PL spectra on temperature indicates that the introduced H2 in the carrier gas can also reduce the carrier localization effect and narrow the energy fluctuation of the well potential, which leads to the narrowed PL spectral width in the samples grown with the mixture of H2/N2 carrier gas. The variation of the PL intensity with respect to temperature reveals that the physical nature of the nonradiative recombination centers at the interface is not influenced by the introduction of H2, but the amount of these centers is greatly reduced, which accounts for the improved emission efficiency. The results of time-resolved PL measurements exhibit that the introduced H2 in the carrier gas has no impact on the nonradiative recombination lifetime, but causes a shorter radiative recombination lifetime, which further confirms the influences of H2 introduction on both QCSE screening and nonradiative recombination centers. The in-depth analyses of the PL results have revealed that the introduction of H2 in the N2 carrier gas for GaN barrier growth can significantly improve the crystalline quality of InGaN/GaN MQWs and therefore enhance the light emission performance. This work has demonstrated PL spectroscopy as a powerful technique in characterizing the optical properties of semiconductor quantum structures, and the spectral findings could provide helpful insight into the growth of InGaN/GaN MQWs.

Full Text

Duke Authors

Cited Authors

  • Wang, T; Liu, JX; Ge, XT; Wang, RX; Sun, Q; Ning, JQ; Zheng, CC

Published Date

  • April 1, 2022

Published In

Volume / Issue

  • 42 / 4

Start / End Page

  • 1179 - 1185

International Standard Serial Number (ISSN)

  • 1000-0593

Digital Object Identifier (DOI)

  • 10.3964/j.issn.1000-0593(2022)04-1179-07

Citation Source

  • Scopus