过渡金属X(X=Cr、Mn、Fe、Tc、Re)掺杂Janus Ga_(2)SSe的第一性原理研究

First-principles study on the transition metal atoms X(X=Cr,Mn,Fe,Tc,Re)doped Janus Ga_(2)SSe materials

利用密度泛函理论的第一性原理赝势平面波方法,研究过渡金属X(X=Cr、Mn、Fe、Tc、Re)原子掺杂Janus Ga_(2)SSe的磁性、电子性质及光学性质.研究表明:过渡金属掺杂Janus Ga_(2)SSe体系在Chalcogen-rich条件下有着比Ga-rich条件下更好的稳定性.其中Mn掺杂体系形成能在两种条件下皆为最低.本征Ga_(2)SSe是具有2.02 eV带隙的间接带隙半导体,在紫外区域有着很好的光伏吸收能力.与本征Ga_(2)SSe相比,Cr掺杂体系自旋向上通道出现杂质能级,自旋向上与向下通道不对称,呈磁矩为2.797μB铁磁性半金属.Mn掺杂体系在其自旋向上通道产生的杂质能级,呈磁矩为3.645μB的磁性P型半导体.Fe掺杂体系自旋向下通道产生的杂质能级,呈磁矩为3.748μB磁性P型半导体.在Tc与Re掺杂后,带隙皆由间接变直接带隙,呈无磁性的P型半导体.从光学性质来看,各掺杂体系与未掺杂Ga_(2)SSe在介电常数和折射系数上相比有着明显的增强,吸收系数在高能量区(3~10 eV)出现蓝移现象.有着在紫外探测器和光伏吸收领域潜在的应用前景.

The magnetic,electronic,and optical properties of transition metal X(X=Cr,Mn,Fe,Tc,Re)a⁃tomically doped Janus Ga_(2)SSe are investigated using the first-principles plane-wave method based on the den⁃sity functional theory.It’s shown that the transition metal-doped Janus Ga_(2)SSe systems have better stability un⁃der Chalcogen-rich condition than under Ga-rich condition.The Mn-doped system has the lowest formation energy under both conditions.The intrinsic Ga_(2)SSe is an indirect bandgap semiconductor with a bandgap of 2.02 eV and has good photovoltaic absorption in the ultraviolet(UV)region.Compared with the intrinsic Ga_(2)SSe,the impurity energy levels appear in the spin-up channel of the Cr-doped system,which makes the spin-up and spin-down channels asymmetric,and presents the ferromagnetic semimetal property with a magnetic moment of 2.797μB.The impurity energy levels appear in the spin-up channel of the Mn-doped system,making the system become a magnetic P-type semiconductor with a magnetic moment of 3.645μB.The impurity energy level appears in the spin-down channel of the Fe-doped system,making the system become a magnetic P-type semiconductor with a magnetic moment of 3.748μB magnetic.After doping of Tc and Re,the band gaps are changed from indirect to direct band gaps,and both systems are non-magnetic P-type semiconductors.In terms of optical properties,each doped system has significantly enhanced dielectric constant and refractive coeffi⁃cient compared with undoped Ga_(2)SSe,and the absorption coefficient appears blue-shifted in the high energy re⁃gion(3-10 eV).It has potential applications in the field of UV detectors and photovoltaic absorption.