[14a-A34-1~7] 13.10 化合物太陽電池

[14a-A34-1] Cd溶媒を用いたTHM法によるV族元素ドープCdTe単結晶成長と評価

〇永岡 章^1,4、Han Kyu-Bun¹、Misra Sudhajit¹、Wilenski Thomas¹、吉野 賢二²、野瀬 嘉太郎³、Scarpulla Michael¹ (1.ユタ大材料工、2.宮崎大工、3.京大院工、4.学振海外特別研究員)

キーワード：化合物太陽電池、カドミウムテルル、II-VI族半導体

Cadmium telluride (CdTe) has been well demonstrated as one of the promising photovoltaic material for solar cells because of its near-optimum bandgap of 1.5 eV and its high absorption coefficient, and is the only II-VI group semiconductor that can be relatively easily doped both p and n type conductivity. Recently, power conversion efficiency >22 % was reported for polycrystalline CdTe cells, but further improvements rely on increasing p-type doping while maintaining long minority carrier lifetime. CdTe solar cells using P-doped bulk crystals as the absorber layer and exhibiting open-circuit voltage (V_OC) >1 V has been reported. Combined experimental and theoretical studies indicate that Cd-rich conditions are needed to achieve long carrier lifetime >10 ns by suppressing Te on Cd antisites, but typical bulk crystal growth is carried out either stoichiometriclaly or in Te solvent. For these reasons, it is important to fundamentally understand bulk group-V doping in CdTe under Cd-rich conditions.