Quantum well intermixing in GaAs-AlGaAs laser structure using sol-gel SiO2 dielectric cap

L. H. Lee*, B. S. Ooi, Y. L. Lam, Y. C. Chan, C. H. Kam

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Intermixing of quantum confined heterostructures, or quantum well intermixing QWI, is an attractive alternative to regrowth and overgrowth techniques for realizing photonic and optoelectronic integrated circuits. Impurity free vacancy diffusion (IFVD) using SiO2 dielectric cap is one of the promising QWI techniques. Silicon dioxide is known to induce outdiffusion of Ga and generate vacancies in GaAs-AlGaAs material during annealing. These vacancies, generated on the group-III sublattice, can be used to promote the diffusion of Al into a buried quantum well (QW) and the diffusion of Ga into the barriers and hence shift the QW band gap to higher energy by partially intermixed the quantum well. The SiO2 layer used in IFVD technique reported to date are typically prepared by plasma enhanced chemical-vapor deposition (PECVD). In this paper, we report the modification of the bandgap energy of GaAs-AlGaAs double quantum well laser structures using SiO2 dielectric cap deposited by sol-gel technique. The effect of the SiO2 thickness on the degrees of intermixing was investigated. The intermixing rate was found to be independent of the dielectric thickness, which implies that surface stress and the solubility limit of Ga in the sol-gel SiO2 are not the main factors responsible for Ga outdiffusion. The effect of Er dopant in the sol-gel SiO2 on the intermixing rate was also studied. The intermixing rate was found to decrease with increasing of Er concentration in the sol-gel SiO2. This observation can be related to the thermal stress effect model.

Original languageEnglish (US)
Pages (from-to)319-323
Number of pages5
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 1998
Externally publishedYes
EventProceedings of the 1998 Conference on Semiconductor Lasers III - Beijing, China
Duration: Sep 16 1998Sep 18 1998

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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