09:15 〜 09:30
▲ [21a-S223-2] Defect Physics in BaSi2 absorber
キーワード：Barium disilicide,Defect physics,First-principles calculation
BaSi2 is a low-cost, earth-abundant compound semiconductor from a silicide family. It has drawn an increasing amount of attentions recently as a candidate thin-film solar cell absorber material. Many promising properties such as ideal optical band gap (1.3 eV), high absorption coefficient (>104 cm-1 for photon energies higher than 1.5 eV), long minority-carrier diffusion length (10 µm) and large quantum efficiency (> 70%) have been reported till date [1-4]. Understanding the fundamental physical properties along with thermodynamic stability and formation mechanism of dominant intrinsic defects of material is crucial for designing and manufacturing efficient solar cells. Therefore, in this study, we investigate the neutral and charged native point defects of BaSi2 by using first-principles density functional theory supercell approach.
From our detailed analysis on formation energies of native defects under appropriate chemical potential conditions of constituent elements, we found that predominant native defects in BaSi2 are silicon vacancy VSi, antisite BaSi and interstitial Sii. On the other hand, antisite SiBa, and interstitial Bai defects are unlikely to form as calculated defect formation energy is very high.
From our detailed analysis on formation energies of native defects under appropriate chemical potential conditions of constituent elements, we found that predominant native defects in BaSi2 are silicon vacancy VSi, antisite BaSi and interstitial Sii. On the other hand, antisite SiBa, and interstitial Bai defects are unlikely to form as calculated defect formation energy is very high.