Abnormal PL spectrum in InGaN MQW surface emitting cavity

J. T. Chu, Y. J. Cheng, Hao-Chung Kuo, Tien-chang Lu, S. C. Wang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We report the observation of an abnormal photoluminescent (PL) spectrum from a HeCd laser pumped InGaN multiple quantum well (MQW) vertical cavity. The device is fabricated using standard MOCVD deposition on a (0001)-oriented sapphire substrate. The layer structures are: 10nm nucleation layer, a 4um bulk GaN layer, InGaN MQWs, and a final 200nm GaN cap layer. The InGaN MQWs consist of 10 pairs of 5 nm GaN barrier and 3 nm In0.1Ga0.9N well. The peak emission of the as-grown MQWs sample was ∼420nm. A dielectric distributed Bragg reflectors (DBR) were then coated on the top layer, followed by a laser lift off from sapphire substrate, and subsequently another DBR coated on the bulk GaN bottom surface. The cavity has a quality factor of ∼520 from 400-490nm. The device was pumped by a focused CW HeCd laser from the bulk GaN side. When the laser is focused onto the InGaN MQWs, a photoluminescent spectrum centered at the designed MQW wavelength was observed as expected. However, when the focused position was moved toward the bulk GaN region, an additional abnormal PL peak around 460nm was observed. This is far outside the designed MQW wavelength.

Original languageEnglish
Title of host publicationVertical-Cavity Surface-Emitting Lasers XII
StatePublished - 15 May 2008
EventVertical-Cavity Surface-Emitting Lasers XII - San Jose, CA, United States
Duration: 23 Jan 200824 Jan 2008

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceVertical-Cavity Surface-Emitting Lasers XII
CountryUnited States
CitySan Jose, CA


  • GaN
  • InGaN
  • MQW
  • Photoluminescence
  • Vertical cavity

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  • Cite this

    Chu, J. T., Cheng, Y. J., Kuo, H-C., Lu, T., & Wang, S. C. (2008). Abnormal PL spectrum in InGaN MQW surface emitting cavity. In Vertical-Cavity Surface-Emitting Lasers XII [69080L] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 6908). https://doi.org/10.1117/12.762869