Current density dependence of transition energy in blue InGaN/GaN MQW LEDs. Issue 5 (17th February 2016)

• Record Type: Journal Article
• Authors: Zhang, F.; Ikeda, M.; Zhou, K.; Liu, Z. S.; Liu, J. P.; Zhang, S. M.; Yang, H.
• Other Names: Zhang Guoyi sponsoringEditor.; Yu Tongjun sponsoringEditor.; Tang Ning sponsoringEditor.; Yang Xuelin sponsoringEditor.; Li Shunfeng sponsoringEditor.
• Is Part Of: Physica status solidi. Volume 13:Issue 5/6(2016:May)
• Page Start: 256
• Page End: 261
• Publication Date: 2016-02-17
• Subjects: InGaN/GaN MQW LED -- transition energy -- QCSE -- band filling -- coupled quantum well; Solid state physics -- Congresses; Solid state physics -- Periodicals; Solid state physics; Conference proceedings; Periodicals; 530.41
• DOI: 10.1002/pssc.201600005
• Languages: English
• ISSNs: 1862-6351

Abstract

Abstract: In this paper we report on the transition energy in InGaN/GaN multiple quantum well (MQW) light emitting diodes (LEDs) under various injection current density from 2 A/cm 2 to 200 A/cm 2 . Various effects including strain, quantum confined Stark effect (QCSE), screening effect by carriers, bandgap renormalization, Stokes‐like shift, band‐filling effect, and quantum levels in triangular quantum wells, are considered quantitatively and analyzed comprehensively. By comparing these effects altogether, we found that when the In‐content in quantum wells is fixed, the transition energy is mainly determined by QCSE and quantum level energy, between which QCSE overweighs the other. The transition energy shift with current density is also mainly governed by the screening effect of QCSE, with detailed competition between band tailing and filling. Additional effect, the coupling between adjacent quantum wells, is investigated in this paper. The coupling between quantum wells with various barrier thicknesses is compared. By calculating the wavefunctions self‐consistently, it is found that for InGaN/GaN MQWs with 5 nm quantum barriers (QBs), the coupling of electron wavefunctions leads to about 2 meV difference in transition energy. While for the MQWs with 3 nm QBs, the influence of electron wave‐function overlap on transition energy is 12.9 meV, which is more significant than that of 5 nm QB case. However, for hole wavefunctions, the coupling effect is too small to be considered, which is mainly due to the much larger effective mass. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)