Analysis of current-voltage characteristics of GaAs/MgO/Fe and InGaAs/MgO/Fe junction

Abstract

Effective spin injection from ferromagnetic metal into semiconductors is essential for the development of spintronics devices. Utilization of effective tunnel barrier helps to overcome the intrinsic conductance mismatch between metal and semiconductor, which is a major source of low electrical spin injection [1]. The GaAs/MgO/Fe [2] and InGaAs/MgO/Fe structures are strong candidates for the spin injection/detection structure with spin filtering effect. These structures are quite attractive since they all can be epitaxially prepared, and especially MgO/Fe structure forms a basic part of Fe(Co)/MgO/Fe(Co) magnetic tunnel junction (MTJ) structure with giant tunneling magnetoresistance (TMR). [3] In this work, we report on the study of current-voltage (I-V) characteristics of the structure, which is important to understand the bias dependent spin filtering phenomena of the structures. The typical rectifying I-V curves clearly show the formation of Schottky barrier at various temperatures, Fig. 1. We estimated bias dependent tunneling barrier height of MgO, varying MgO thickness and then Schottky barrier, varying temperature. Thereafter, the ratio of tunneling current to thermionic Schottky emission is calculated since these two transport mechanisms need to be focused to find favorable transport regions for spin injection through MgO barrier.