Magneto-optical spectra and the presence of an impurity band in p-type ferromagnetic semiconductor (Ga,Fe)Sb with high Curie temperature

Karumuri Sriharsha,Shobhit Goel,Nguyen Thanh Tu,Le Duc Anh,Masaaki Tanaka

doi:10.1063/1.5083175

Karumuri Sriharsha, Shobhit Goel + Show 3 more

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https://doi.org/10.1063/1.5083175

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Journal: APL materials	Publication Date: Feb 1, 2019
Citations: 12	License type: cc-by

Affiliation: The University of Tokyo

Abstract

By using magnetic circular dichroism (MCD) spectroscopy with photon energy in both visible (1.5–5 eV) and infrared light regions (0.6–1.7 eV), we systematically investigate the band structure of p-type ferromagnetic semiconductor (Ga1−x,Fex)Sb with various Fe concentrations x = 2%–20% grown by low-temperature molecular beam epitaxy. We observed two peaks in the infrared MCD spectra that can be explained by the optical transitions related to the Fermi level (EF) located in an Fe-related impurity band (IB) in the bandgap. As x increases, the energy shifts of the two peaks suggest that the Fe-related IB extends into the bandgap and EF rises correspondingly. Furthermore, the mobility of hole carriers in these (Ga,Fe)Sb thin films estimated by Hall measurements is very low (0.2–2 cm2/Vs), which is consistent with our conclusion that the hole carriers and EF reside in the IB rather than in the valence band. Our results provide insights into the band structure of p-type ferromagnetic semiconductors (Ga,Fe)Sb with high Curie temperature, which is promising for the realization of spintronic devices operating at room temperature.

Highlights

In order to overcome these problems in Mndoped III-V Ferromagnetic semiconductors (FMSs), we created a new class of FMSs using Fe as the magnetic dopant, namely, narrow-gap Fe-doped III-V FMSs.12–22 In Fe-doped III-V FMSs, the Fe concentration and carrier concentration can be controlled independently since Fe atoms are mainly isoelectronic in III-V semiconductors
By using magnetic circular dichroism (MCD) spectroscopy with photon energy in both visible (1.5–5 eV) and infrared light regions (0.6–1.7 eV), we systematically investigate the band structure of p-type ferromagnetic semiconductor (Ga1−x,Fex)Sb with various Fe concentrations x = 2%–20% grown by low-temperature molecular beam epitaxy
The mobility of hole carriers in these (Ga,Fe)Sb thin films estimated by Hall measurements is very low (0.2–2 cm2/Vs), which is consistent with our conclusion that the hole carriers and EF reside in the impurity band (IB) rather than in the valence band

Summary

Introduction

In order to overcome these problems in Mndoped III-V FMSs, we created a new class of FMSs using Fe as the magnetic dopant, namely, narrow-gap Fe-doped III-V FMSs.12–22 In Fe-doped III-V FMSs, the Fe concentration and carrier concentration can be controlled independently since Fe atoms are mainly isoelectronic in III-V semiconductors.

Results

Conclusion