The thickness design of unintentionally doped GaN interlayer matched with background doping level for InGaN-based laser diodes

• Published in: AIP advances 2016-03, Vol.6 (3), p.035124-035124-9
• Main Authors: Chen, P., Zhao, D. G., Jiang, D. S., Zhu, J. J., Liu, Z. S., Yang, J., Li, X., Le, L. C., He, X. G., Liu, W., Li, X. J., Liang, F., Zhang, B. S., Yang, H., Zhang, Y. T., Du, G. T.
• Format: Article
• Language: English
• Subjects: ABSORPTION; ALUMINIUM COMPOUNDS; CONCENTRATION RATIO; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DEPLETION LAYER; DESIGN; DOPED MATERIALS; Doping; ELECTRONIC STRUCTURE; ELECTRONS; GALLIUM COMPOUNDS; GALLIUM NITRIDES; INDIUM COMPOUNDS; Indium gallium nitrides; INTERFACES; Interlayers; Lasers; LOSSES; Matching; NITROGEN COMPOUNDS; QUANTUM WELLS; SEMICONDUCTOR LASERS; THICKNESS; VISIBLE RADIATION
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/1.4945015

In order to reduce the internal optical loss of InGaN laser diodes, an unintentionally doped GaN (u-GaN) interlayer is inserted between InGaN/GaN multiple quantum well active region and Al0.2Ga0.8N electron blocking layer. The thickness design of u-GaN interlayer matching up with background doping level for improving laser performance is studied. It is found that a suitably chosen u-GaN interlayer can well modulate the optical absorption loss and optical confinement factor. However, if the value of background doping concentration of u-GaN interlayer is too large, the output light power may decrease. The analysis of energy band diagram of a LD structure with 100 nm u-GaN interlayer shows that the width of n-side depletion region decreases when the background concentration increases, and may become even too small to cover whole MQW, resulting in a serious decrease of the output light power. It means that a suitable interlayer thickness design matching with the background doping level of u-GaN interlayer is significant for InGaN-based laser diodes.