Photoreflectance of Zn:AlxGa1xAs at the E1 Transition Energy as a Function of Carrier Concentration and Aluminum Composition
Abstract
The photoreflectance (PR) spectra of MOCVD grown Zn:AlxGa1xAs with 0 < x < 0.55 and carrier concentration, N, of 5 × 1017 to 1 × 1019 cm3 was studied at the E1 transition energy. Of particular interest was the effect of varying N and x on E1, the broadening of the Γ1 structure. Within the experimental error, Γ1 was found to increase as x increases. The slope of Γ1 with log(N) initially decreases as x is increased to 0.29, which is possibly due to a decrease in the translational periodicity of the sample. For 0.30 < x < 0.39, the slope increases sharply which may be due to an increase in the nearsurface field with increasing N and decrease in the static dielectric constant, s. The drop of the slope in the region 0.40 < x < 0.49 is probably due to the “crossover region” behavior of AlxGa1xAs from direct to indirect band. After the transition is crossed over, the slope again shows an upward trend in the range 0.50 < x < 0.55, as expected.
 Publication:

Physica Scripta
 Pub Date:
 2001
 DOI:
 10.1238/Physica.Regular.064a00386
 Bibcode:
 2001PhyS...64..386S
 Keywords:

 78.20.e;
 78.30.Fs;
 78.40.Fy;
 78.55.Cr