Contactless electroreflectance studies of the band filling effect in Ga1-xMnxAs
Journal
Physica E-Low-Dimensional Systems & Nanostructures
Journal Volume
32
Journal Issue
1-2
Pages
387-390
Date Issued
2006
Author(s)
Abstract
Contactless electroreflectance (CER) method was used to study the properties of Ga1 - x Mnx As samples with x = 0.014 - 0.068. From superconducting quantum interference device (SQUID) measurement, the ferromagnetic transition temperature was found to range from 50 to 100 K for these samples. In the CER experiment, in addition to the features commonly observed for GaAs, above band gap feature could be observed at low temperature for some of the samples. The appearance of the above band gap feature is interpreted as due to the band filling effect of holes in the valence band of Ga1 - x Mnx As layer. The large amount of free holes raises the Fermi level of the Ga1 - x Mnx As above the band edge of the valence band and increases the effective bandgap observed in the CER measurement. The Fermi level obtained from the measurement is around 30 meV which corresponds to a free hole concentration of around 3 × 1019 cm- 3. The results indicate that the Fermi level of metallic Ga1 - x Mnx As resides in the valence band and is an ordinary metal. © 2006 Elsevier B.V. All rights reserved.
Type
journal article