Photoreflectance study of strained InAlAs/InP structures

Jenn Shyong Hwang, W. Y. Chou, S. L. Tyan, Y. C. Wang, J. H. Tung

Research output: Contribution to journalConference articlepeer-review


We have studied the photoreflectance spectra at 300 K from a series of strained In1-xAlxAs/InP (0.42<x<0.57) strained structures grown by molecular beam epitaxy. From the observed Franz-Keldysh Oscillation we evaluate the built-in dc electric field and hence the surface potential under different strain. We found that the surface Fermi level is not pinned at midgap under different strain, which results in contrast to AlGaAs and GaAs. In addition, from the observed dependence of the built-in electric field Fdc and surface potential barrier Vm on the top layer thickness, we conclude that the surface states are distributed over two separate regions within the energy band gap under different strain and the densities of the surface states are as low as (2.71 ± 0.05)× 1011 cm-2 for the distribution near the conduction band and (4.29 ± 0.05)× 1011 cm-2 for the distribution near the valence band. The Fermi level is weakly pinned while the top layer thickness is within the characteristic region of each sample.

Original languageEnglish
Pages (from-to)217-222
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Publication statusPublished - 1995 Dec 1
EventProceedings of the 1995 MRS Spring Meeting - San Francisco, CA, USA
Duration: 1995 Apr 171995 Apr 20

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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