Theoretical Research On P Type Of ZnS Doping And Optical Properties

Including the intrinsic ZnS,N,P,As doped system,ZnS(Cu,N)system,ZnS(Cu,P)system and ZnS(Cu,As)system,which have been calculated by using density functional theory based on first-principles plane wave ultrasoft pseudopotential method and general gradient approximation(GGA).The results are as follows.Intrinsic ZnS material is a dierct gap semiconductor,whose bandgap is 2.134 eV.It is difficult to get p-type doped ZnS,because of the valence band holes with large effective mass.According to the calculation results,which show that N-doped ZnS is formed by the main acceptorlevel,its hole bound state colse to the top of the valence band stateis is not easy to ionize,enhance the locality of states.Due to lower concentration and stability,it is not easy to be obtained for ideal p-type ZnS.In further,comparing with N-doped system,p-doped and As doped ZnS have no obvious widening,less valence electronics,no much big gap and more stable,which led to the formation of p-type ZnS.ZnS(Cu,N)as compared with N-doped system,show that co-doping system decrease the bandgap,have more great stability.By analysis the results of total densities,which show that the states near Fermi energy become more diffuse and go through the energy,so it is conduct to the formation of p-ZnS.In addition to,comparing with p-doped and As-doped ZnS system respectively,ZnS(Cu,P)and ZnS(Cu,As)become more stable,the gap decrease and also have the state density peak broadening of different levels,which mainly result from the hybrid orbital effects of state S-3p and N-2p,P-3p,As-4p,which proved that co-doping ZnS system have smaller bandgap than the single doped ZnS system,which is more suitable for realizing the P-type ZnS.Through the analysis of ZnS(Cu,N),ZnS(Cu,P),ZnS(Cu,As)system on lattice parameters,the band structure,the state densities,when the doping ratio of the Cu and N,P,As is 1:2,which make the gap decrease,reduce the transition energy and enhance the possibility of transition that between the Valance band and conduction band.So it is conduct to improve the absorption ration of solar.