Design and Characterization of a Sharp GaAs/Zn(Mn)Se Heterovalent Interface: A Sub-Nanometer Scale View.

Davide F Grossi,Mikhail N Drozdov,Alexey A Toropov,Sergey V Sorokin,Sergey V Ivanov,Pavel A Yunin,Andrei Y Silov,Paul M Koenraad,Grigory V Klimko,Sebastian Koelling

doi:10.3390/nano10071315

Abstract

The distribution of magnetic impurities (Mn) across a GaAs/Zn(Mn)Se heterovalent interface is investigated combining three experimental techniques: Cross-Section Scanning Tunnel Microscopy (X-STM), Atom Probe Tomography (APT), and Secondary Ions Mass Spectroscopy (SIMS). This unique combination allowed us to probe the Mn distribution with excellent sensitivity and sub-nanometer resolution. Our results show that the diffusion of Mn impurities in GaAs is strongly suppressed; conversely, Mn atoms are subject to a substantial redistribution in the ZnSe layer, which is affected by the growth conditions and the presence of an annealing step. These results show that it is possible to fabricate a sharp interface between a magnetic semiconductor (Zn(Mn)Se) and high quality GaAs, with low dopant concentration and good optical properties.

Highlights

Diluted Magnetic Semiconductors (DMS) are an interesting class of materials, obtained by adding a small concentration of magnetic dopants in a semiconductor (e.g., Ga(Mn)As) [1]
The magnetic impurities (Mn) profile can be described with a combination of two error functions, which describe the diffusion at the front tail and at the back tail of the MnSe thin film
The diffusion of Mn atoms in GaAs is limited to a few nanometers from the interface of the MnSe layer, with a diffusion length λ = 0.3 nm

Summary

Introduction

Diluted Magnetic Semiconductors (DMS) are an interesting class of materials, obtained by adding a small concentration of magnetic dopants in a semiconductor (e.g., Ga(Mn)As) [1]. These materials have many potential applications in the field of spintronics, including devices with high speed and low power consumption [2], magneto-optical devices [3], and semiconductor based spin valves [4,5]. One of the challenges in this field is to create DMS with strong magnetic response (i.e., showing ferromagnetic [6] or superparamegnetic [7] properties), without compromising the opto-electronic properties of the semiconductor. Heterostructures of III–V/II–VI semiconductor materials are a promising system to fabricate such structures [11]

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