In situ reflectance monitoring for the MOVPE of strain-balanced InGaAs/GaAsP quantum-wells

Yunpeng Wang, Ryusuke Onitsuka, Momoko Deura, Wen Yu, Masakazu Sugiyama, Yoshiaki Nakano

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

A strain-balanced InGaAs/GaAsP multiple quantum-wells (MQWs) structure was grown by metal organic vapor phase epitaxy (MOVPE) on GaAs substrate, aiming at a middle cell that improves current matching in a tandem solar cell. In order to detect the instant of strain relaxation in the course of MOVPE, which deteriorates crystal quality significantly, we employed in situ optical surface reflectivity measurement. When strain balancing was incomplete, surface reflectivity dropped during the growth of MQWs, indicating lattice relaxation. Such drop in surface reflectivity occurred at a smaller number of stacked quantum wells when the absolute value of an average strain per well/barrier pair was larger. The accumulated strain, i.e., the product between the average strain and the total thickness at the moment of reflectivity dropped, was roughly constant for all the MQWs, indicating a possibility that we can use this value as the measure to predict the maximum number of MQWs for a given value of the average strain. The reflectance anisotropy (RA) was also monitored in the course of the growth. The value of RA showed linear periodic behavior before the lattice relaxation, corresponding to the well/barrier stacks, suggesting that anisotropy of surface atoms reflects accumulated strain of the growth surface.

Original languageEnglish
Pages (from-to)1364-1369
Number of pages6
JournalJournal of Crystal Growth
Volume312
Issue number8
DOIs
Publication statusPublished - 2010 Apr 1

Keywords

  • A1. Surface structure
  • A3. Metalorganic vapor phase epitaxy
  • B1. Gallium arsenic
  • B2. Semiconducting III-V materials

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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