u掺杂的Hg0.75Cd0.25Te材料电子结构影响的第一性原理研究

he structural and electronic properties of the gold in-situ impurity (AuHg) and gold interstitial defect (Aui) in Hg0.75Cd0.25Te (MCT) have been studied by plane-wave pseudopotential methods based on the density functional theory. Valence charge density, electron localization function (ELF), density of states and formation energy of gold impurity and defect were calculated to reveal the dopant stability and doping efficiency. The results indicate that the in-situ gold impurity maintains a relative strong bonding with the host atom. The impurity AuHg creates a shallow acceptor level that is 23 meV above VBM. However, the interstitial gold defect is dominant donor. Under Hg-rich MBE growth condition, due to the self-compensating effect between AuHg and Aui, the Fermi level is pinned close to CBM by which the gold impurity cannot behave as an efficient acceptor.Whereas under Te-rich MBE growth condition and LPE growth condition, the self-compensating effect is overcame and the in-situ gold impurity acts as an efficient p-type dopant.