MnTe/CdTe interfaces characterisation: a magneto-optical study

Abstract

This paper is devoted to the description of the interface between MnTe and CdTe, and to its magneto-optical properties. Indeed, the epitaxy of an heterojunction with these two II–VI semiconductors tends to form a few monolayers of Cd1−xMnxTe, which is a well known semimagnetic semiconductor very sensitive to a magnetic field [1]. Thus, thanks to the enhanced giant Zeeman splitting of the excitonic line observed in MnTe/CdTe heterostructures under a magnetic field, we have a very powerful tool for probing the quality of this interface at the atomic scale. Systematic studies can be performed in order to analyse the influence of different growth conditions. It is shown that the magnetic properties of MnTe/CdTe interfaces grown at 280°C are mainly due to an exchange between Mn and Cd atoms that occurs, during the growth, between the last incorporated monolayer and the one being grown. Thanks to a modelisation of the kinetics effects in the Mn segregation process, we can compute the Mn concentration profile monolayer by monolayer. We are then able to ‘quantify’ the experimentally observed influence of the substrate temperature, of the impinging fluxes, of the growth method, and finally of the cations involved at the interfaces, on the Mn segregation process. By optimising all these parameters, we show how to control the abruptness of the MnTe/CdTe interfaces.