Wet thermal oxidation of AlxGa1−xAs compounds

Abstract

Results are presented on the wet thermal oxidation of AlxGa1−xAs. The growth of wet thermal oxides of AlxGa1−xAs is shown to be linear with time. An O2 carrier gas was found to form a self-terminating oxide for compositions investigated (x≳0.4), but required elevated temperatures for substantial growth. The use of a medium oxygen concentration (∼20%) in a N2 carrier formed nonuniform oxides for all compositions investigated. A low O2 concentration (0.1%) in the N2 carrier was found to reduce the activation energy of the oxidation process for Al0.6Ga0.4As from 1.9 to 1.0 eV while increasing the activation energy of Al0.8Ga0.2As from 1.6 to 1.75 eV. For these wet thermal oxides it is observed that lateral oxidation at heterojunction interfaces is enhanced. This enhanced lateral oxidation can be attributed to local stress due to the smaller volume of the growing oxide compared to the volume of the consumed semiconductor.

Lateral wet oxidation of AlxGa1−xAs-GaAs depending on its structures

“…Then the kinetics of lateral oxidation can be changed due to the effect of heterointerfaces. 10,11 Linear growth rates were reported for lateral oxidation of Al 0.98 Ga 0.02 As. 12 Meanwhile, it has been recently reported for lateral oxidation of AlAs that the initial oxide growth is linear with time and converts to parabolic growth with increasing oxide thickness.…”

“…This stress can enhance the lateral oxidation. 10 Here enhanced lateral oxidation is reduced using Al 0.72 Ga 0.28 As intermediate layers. The Al 0.72 Ga 0.28 As would also serve as a partial oxidation-stop layer because the oxidation rate is significantly lower by ϳ100 times ͑see Fig.…”

Effect of cylindrical geometry on the wet thermal oxidation of AlAs

“…Although VCSELs frequently employ circular mesas, most of the oxidation rate studies to date have been conducted with stripes. [5][6][7][8][9] In this article, we describe a model for the oxidation of circular mesas. Our model differs from one previously reported, 10 and we believe it more accurately includes the effect of cylindrical geometry upon the oxidation process.…”

Controlled steam oxidation of AlInAs for microelectronics and optoelectronics applications

“…The activation energies for lateral and vertical oxidation come out as 1.38 9 and 1.85 eV 10 , respectively, which are similar to the values reported for AlGaAs with the same Al content. 11 A discrepancy between the lateral and vertical oxidation rate has been reported. 11 A discrepancy between the lateral and vertical oxidation rate has been reported.…”