Au掺杂Hg_(3)In_(2)Te_(6)成键机制与电子性质的第一性原理研究

First-Principles Study on Bonding Mechanism and Electronic Properties of Au Doped Hg_(3)In_(2)Te_(6)

Hg_(3)In_(2)Te_(6)(简称MIT)是Ⅱ-Ⅵ/Ⅲ-Ⅵ族化合物半导体Hg_(3-3x)In_(2x)Te_(3)中x=0.5时对应的稳定相。本文采用第一性原理方法,系统地探究了Au在MIT中的稳定性和掺杂效率。计算结果表明:Au—Te键具有与Hg—Te相似的极性共价键特性,表明Au在MIT中具有一定掺杂稳定性。此外,发现Au在MIT中存在两性掺杂特性:Au在Au_(Hg)和Au_(In)体系中表现受主特性,Au-5d电子轨道分别在价带顶和-4 eV位置与Te-5p电子轨道形成共振,形成受主杂质能级;而Au在Au_(Te)和Au_(I)体系中表现施主特性,Au-5d与Hg-6s、In-5s电子轨道在导带底产生共振,形成施主杂质能级。富Hg条件下,Au_(I)、Au_(Te)与Au_(Hg)之间会产生自我补偿效应,费米能级被钉扎在价带顶,而富Te条件下,上述自我补偿效应将会得到有效消除。

Hg_(3)In_(2)Te_(6)(MIT for short)is a stable phase corresponding to x=0.5 in theⅡ-Ⅵ/Ⅲ-Ⅵcompound semiconductor Hg_(3-3x)In_(2x)Te_(3).In this paper,the stability and doping efficiency of Au in MIT were systematically investigated using the first-principles method.The results show that Au-Te bonds has polar covalent bond characteristics similar to that of Hg-Te bonds in MIT,indicating that Au has certain doping stability in MIT.In addition,it is found that there are amphoteric doping properties of Au in MIT:Au exhibits acceptor properties in Au_(Hg) and Au_(In) systems,and the Au-5d electron orbital resonates with the Te-5p electron orbital at the top of the valence band and-4 eV position,respectively,forming acceptor defect levels.While Au exhibits donor characteristics in Au_(Te) and Au_(I) systems,Au-5d resonates with Hg-6s and In-5s electron orbitals at the conduction band bottom,forming donor defect levels.It is worth noting that under Hg-rich conditions,there will be a self-compensation effect between Au_(I),Au_(Te) and Au_(Hg) systems,and the Fermi level will be pinned at the top of valence band,while under Te-rich conditions,the self-compensation effect will be effectively eliminated.