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Science 28 July 1989:
Vol. 245. no. 4916, pp. 391 - 393
DOI: 10.1126/science.245.4916.391
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Articles

GaAs Clusters in the Quantum Size Regime: Growth on High Surface Area Silica by Molecular Beam Epitaxy

C. J. SANDROFF , J. P. HARBISON , R. RAMESH , M. J. ANDREJCO , M. S. HEGDE , C. C. CHANG , E. M. VOGEL , and D. M. HWANG 1

1 Solid State Chemistry Unit, Indian Institute of Science, Banglore, India.

Molecular beam epitaxy has been used to grow microcrystalline clusters of gallium arsenide (GaAs) in the size range from 2.5 to 60 nanometers on high-purity, amorphous silica supports. High-resolution transmission electron microscopy reveals that clusters as small as 3.5 nanometers have good crystalline order with a lattice constant equal to that of bulk GaAs. Study of the microcrystallite surfaces by x-ray photoelectron spectroscopy shows that they are covered with a shell (1.0 to 1.5 nanometers thick) of native oxides of gallium and arsenic (Ga2O3 and As2O3), whose presence could explain the low luminescence efficiency of the clusters. Optical absorption spectra of the supported GaAs are consistent with the blue-shifted band edge expected for semiconductor microcrystallites in the quantum size regime.

Submitted on May 8, 1989
Accepted on June 9, 1989


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Luminescent Colloidal Silicon Suspensions from Porous Silicon.
J. L. HEINRICH, C. L. CURTIS, G. M. CREDO, M. J. SAILOR, and K. L. KAVANAGH (1992)
Science 255, 66-68
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Science. ISSN 0036-8075 (print), 1095-9203 (online)