Photoreflectance Study of the Fundamental Optical Properties of (Ga,Mn)As Epitaxial Films

TL;DR

This study uses photoreflectance spectroscopy combined with other techniques to analyze the optical and electronic properties of (Ga,Mn)As films with varying Mn content, revealing how Mn influences the band structure.

Contribution

It provides a detailed analysis of the band structure evolution in (Ga,Mn)As films with different Mn concentrations using full-line-shape PR spectra analysis.

Findings

Significant differences in electronic transition energies between low and high Mn content films.

Evidence of merging Mn impurity band with GaAs valence band at higher Mn levels.

Detailed characterization of the valence band structure evolution with Mn doping.

Abstract

Fundamental optical properties of thin films of (Ga,Mn)As diluted ferromagnetic semiconductor with a low (1%) and high (6%) Mn content and of a reference GaAs film, grown by low-temperature molecular-beam epitaxy, have been investigated by photoreflectance (PR) spectroscopy. In addition, the films were subjected to complementary characterization by means of superconducting quantum interference device (SQUID) magnetometry, Raman spectroscopy, and high resolution X-ray diffractometry. Thorough full-line-shape analysis of the PR spectra, which enabled determination of the E0 electronic transition in (Ga,Mn)As, revealed significant differences between the energy band structures in vicinity of the {\Gamma} point of the Brillouin zone for the two (Ga,Mn)As films. In view of the obtained experimental results the evolution of the valence band structure in (Ga,Mn)As with increasing Mn content is discussed, pointing to a merging the Mn-related impurity band with the host GaAs valence band for high Mn content.