Zheng Yu Jie, Zhang Qi, Odunmbaku Omololu, Ou Zeping, Li Meng, Sun Kuan
Key Laboratory of Low-grade Energy Utilization Technologies and Systems of the Ministry of Education of China, Chongqing University, Chongqing 400044, People's Republic of China.
School of Energy and Power Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
J Phys Condens Matter. 2021 Dec 1;34(8). doi: 10.1088/1361-648X/ac3691.
Utilizing first-principles calculations, charge transfer doping process of single layer tin selenide (SL-SnSe) via the surface adsorption of various organic molecules was investigated. Effective p-type SnSe, with carrier concentration exceeding 3.59 × 10 cm, was obtained upon adsorption of tetracyanoquinodimethane or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane on SL-SnSe due to their lowest unoccupied molecular orbitals acting as shallow acceptor states. While we could not obtain effective n-type SnSe through adsorption of tetrathiafulvalene (TTF) or 1,4,5,8-tetrathianaphthalene on pristine SnSe due to their highest occupied molecular orbitals (HOMO) being far from the conduction band edge of SnSe, this disadvantageous situation can be amended by the introduction of an external electric field perpendicular to the monolayer surface. It is found that Snwill facilitate charge transfer from TTF to SnSe through introducing an unoccupied gap state just above the HOMO of TTF, thereby partially compensating for the p-type doping effect of Sn. Our results show that both effective p-type and n-type SnSe can be obtained and tuned by charge transfer doping, which is necessary to promote its applications in nanoelectronics, thermoelectrics and optoelectronics.
利用第一性原理计算，研究了单层硒化锡（SL-SnSe）通过各种有机分子的表面吸附进行电荷转移掺杂的过程。在SL-SnSe上吸附四氰基对苯二醌二甲烷或2,3,5,6-四氟-7,7,8,8-四氰基对苯二醌二甲烷后，由于它们的最低未占据分子轨道充当浅受主态，获得了载流子浓度超过3.59×10¹⁹ cm⁻³的有效p型SnSe。虽然由于四硫富瓦烯（TTF）或1,4,5,8-四硫代萘的最高占据分子轨道（HOMO）远离SnSe的导带边缘，我们无法通过在原始SnSe上吸附它们来获得有效的n型SnSe，但这种不利情况可以通过引入垂直于单层表面的外部电场来改善。研究发现，通过在TTF的HOMO上方引入一个未占据的能隙态，Sn将促进电荷从TTF转移到SnSe，从而部分补偿Sn的p型掺杂效应。我们的结果表明，通过电荷转移掺杂可以获得并调控有效的p型和n型SnSe，这对于促进其在纳米电子学、热电学和光电子学中的应用是必要的。
