中文摘要：

基于密度泛函理论的第一性原理方法,通过形成能和束缚能的计算研究了B在Hg_（0.75）Cd_（0.25）Te中的掺杂效应.结果表明B在Hg_（0.75）Cd_（0.25）Te中存在着两种主要形态：第一种是在完整的Hg_（0.75）Cd_（0.25）Te材料中B稳定存在于六角间隙位置而非替位.此时,B形成容易激活的三级施主使材料表现为n型.另一种是在有Hg空位存在的Hg_（0.75）Cd_（0.25）Te中B更容易与Hg空位结合形成缺陷复合体,其束缚能达到了0.96 eV这种复合体在Hg_（0.75）Cd_（0.25）Te材料中形成单施主也使材料表现为n型.考虑到辐照损伤形成的Hg空位受主,这种B与Hg空位的复合体是制约B离子在MCT中注入激活的一个重要因素.

英文摘要：

Using the first-principles method based on the density functional theory,we study the doping effect of B impurity in HgCdTe （MCT）.We find that the most stable configuration of the impurity is at the B hexagonal interstitial position,rather than at the in-situ substitution.The electronic structures and the density of states of B hexagonal interstitial doped MCT are systematically investigated. Near neighbour（NN） and next-near-neighbor（NNN） atoms around the B impurity are obviously relaxed.The relaxation induces the breaking of NN Te-Hg covalent bond.Moreover,B hexagonal interstitial behaves as triple n-type dopant.The charged state analysis indicates that B_i~h（2Hg1Cd） with three positive charges is most stable and forms an effecient donor.However,as long as the Hg vacancy exists,complex impurity between Hg vacancy and B impurity can be easily formed,its binding energy reaches up to 0.96 eV.Such complex behaves as single n-type dopant.Considering radiation damage of B ion implantation,the complex is a main factor restricting the activation of B ion in MCT.