外加电场和B/N掺杂对锡烯带隙的影响

Influcence of external electric field and B/N doping on the band gap of stanene

锡烯具有超高载流子密度、无质量狄拉克费米子和高导热性等优良性质,并且存在能带反转现象,被认为是拓扑绝缘体,拓扑绝缘体在一定条件下可以获得无耗散电流,具有极高的应用潜力.由于锡烯在布里渊区高对称点K处的能带存在狄拉克锥,带隙为零,大大限制了锡烯在半导体领域的应用.本文采用在锡烯中掺杂B/N元素和在垂直于锡烯平面方向施加电场的方法来打开锡烯在K点处的带隙,并研究掺杂和施加电场强度对锡烯结构和电子性质的变化.研究发现施加掺杂B元素和垂直电场都能在保留锡烯拓扑性质的同时打开K点处的带隙,并且施加的垂直电场强度与K点处带隙呈正相关.在掺杂B元素的同时施加垂直电场可以增大K点处的带隙,当电场强度为0.5 V/A时,带隙达到0.092 eV.掺杂N元素后,锡烯变为间接带隙半导体,带隙为0.183 eV.施加垂直电场不能改变N元素掺杂锡烯的结构,施加的垂直电场强度与K点处带隙则呈负相关,当电场强度为0.5 V/A时,K点处带隙减小到0.153 eV.

Stanene possesses excellent properties,including an extremely high charge carrier density,massless Dirac fermions,and high thermal conductivity.Moreover,it exhibits band inversion phenomena,being made a candidate for a topological insulator.Topological insulators can generate dissipationless electric currents under certain conditions,showing great application potentials.However,the presence of a Dirac cone in the band structure of stanene at the high-symmetry point K in the Brillouin zone,resulting in a zero band gap,significantly limits its applications in the semiconductor field.This study adopts the method of doping B/N elements in stanene and applying an electric field perpendicular to the stanene to open the band gap at the K point.The effects of doping and the intensity of the applied electric field on the structural and electronic properties of stanene are investigated.The results reveal that both doping B elements and applying a vertical electric field can open the band gap at the K point while preserving the topological properties of stanene.Additionally,there is a positive correlation between the applied vertical electric field intensity and the band gap at the K point.Simultaneously doping B elements and applying a vertical electric field can increase the band gap at the K point,reaching 0.092 eV when the electric field intensity is 0.5 V/A.After doping N elements,stanene is transformed into an indirect band gap semiconductor with a band gap of 0.183 eV.Applying a vertical electric field cannot change the structure of N-doped stanene,and the intensity of the applied vertical electric field is negatively correlated with the band gap at the K point.When the electric field intensity is 0.5 V/A,the band gap at the K point decreases to 0.153 eV.