Optimizing GaN/AlGaN multiple quantum well structures by time-resolved photoluminescence

J. Li, K. C. Zeng, E. J. Shin, J. Y. Lin, H. X. Jiang

Research output: Contribution to journalConference articlepeer-review

Abstract

We present the results of picosecond time-resolved photoluminescence (PL) measurements for GaN/AlxGa1-xN MQWs with varying structural parameters, grown by metalorganic chemical vapor deposition under the optimal GaN-like growth conditions. We have shown that the optimal GaN/AlGaN (x ∼ 0.2) MQW structures for UV light emitter applications are those with well widths ranging from 12 and 42 Å and barrier widths ranging from 40 to 80 Å. The decreased quantum efficiency in GaN/AlxGa1- xN MQWs with well width Lw<12 Å is due to the enhanced carrier leakage to the underlying GaN epilayers, while the decreased quantum efficiency in MQWs with well width Lw>42 Å is associated with an increased nonradiative recombination rate as Lw approaching the critical thickness of MQWs. For the barrier width dependence, when the barrier width is below the critical thickness, the nonradiative recombination rate increases with a decrease of the barrier width due to the enhanced probabilities of the electron and bole wavefunctions at the interfaces as well as in the AlGaN barriers. On the other hand, the misfit dislocation density increases as The barrier width approaches the critical thickness, which can result in an enhanced nonradiative interface recombination rate. Our optimized GaN/AlxGa1-xN MQW structures exhibited extremely high quantum efficiencies as well as a ratio of well emission intensity to barrier emission intensity exceeding 104.

Original languageEnglish
Pages (from-to)70-77
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4280
DOIs
StatePublished - 2001
EventUltrafast Phenomena in Semiconductors V - San Jose, CA, United States
Duration: Jan 25 2001Jan 26 2001

Keywords

  • GaN/AlGaN quantum wells
  • Optical transitions
  • Time-resolved PL
  • UV light emitters
  • Wide bandgap

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