Ab Initio Study of MgSe Self-Interstitial (Mgi and Sei)

Abstract

We present detailed calculations of formation and thermodynamics transition state energies of Mgiand Seiinterstitial defects in MgSe using generalized gradient approximation (GGA) and local density approximation (LDA) functional in the frame work of density functional theory (DFT). For both LDA and GGA the formation energies of Mgiand Seiare relatively low in all the configurations. The most stable Se interstitial was the tetrahedral (T) configuration having lower formation energy than the decagonal (D) configuration. TheMgiand Seidefect introduced transition state levels that had either donor or acceptor levels within the band gap. Seiacts as a donor or an acceptor and creates levels that were either deep or shallow depending on the configuration. Seiexhibit negative-U properties and show charge states metastability in the D configuration. Mgiacts as only shallow donor (+2/ + 1) in both T and D configurations, in addition we pointed out the role of Mgias electrically activating donor.