Defect physics of CuInSe 2 chalcopyrite semiconductor Yoshida-lab Hiroki Uede S. B. Zhang, Su-Huai Wei, Alex Zunger, H. Katayama-Yoshida, Phys. Rev. B 57, 9642 (1998). Defect ( 欠陥 ) Chalcopyrite semiconductor ( カルコパイライト型半導体 )

Contents I.Introduction II.Calculation method III.Calculation results IV.Summary V.My work

Application of CuInSe 2 and motivation 山口真史他 著 『太陽電池の基礎と応用』 丸善株式会社 visible light p-type conductor at high doping ? Photovoltaic solar cell high absorption coefficient high efficiency self-healing create p- and n-type CuInSe 2 crystal superconducting matter? Photovoltaic solar cell ( 太陽光発電 ) Absorption coefficient ( 吸収係数 ) Superconducting matter ( 超伝導物質 )

cation anion Chalcopyrite structure cation1 cation2 anion What is Chalcopyrite structure? Diamond structure Zinc-blende structure ×2 閃亜鉛鉱型構造

CuInSe 2 Chalcopyrite semiconductor Experimental energy gap =1.04[eV] (direct gap) Lattice parameter a=5.786[Å] η=c/a=2.016 c a Cu In Se Copper Indium Diselenide for Photovoltaic Applications, edited by T. J. Coutts, L. L. Kazmerski, and S. Wagner (Elsevier, Amsterdam,1986).

Details Cu In Se In Cu V Cu V In Cu In Cu i Defect formation energy ( 欠陥生成エネルギー ) Vacancy of atom ( 原子空孔 ) Antisite ( 逆サイト ) Interstitial ( 格子間 ) V Cu,V In :vacancy of atom Cu, In In Cu :antisite of atom In on site Cu Cu In :antisite of atom Cu on site In Cu i :Cu type interstitial

Defect formation energy for a neutral(q=0) defect q CuInSe 2 crystal defect atom electron thermal equilibrium ( 熱平衡 )

Defect formation energy for a charge(q≠0) defect q CuInSe 2 crystal defect atom electron

Limits of Fermi energy and atomic chemical potential Fermi energy bound between the valence band maximum(VBM) and conduction band minimum(CBM) CBM VBM Energy gap Valence band Conduction band Chemical potential valence band ( 価電子帯 )=HOMO conduction band ( 伝導帯 )=LUMO

Defect transition energy level Defect transition energy level ( 欠陥遷移エネルギー準位 )

Computational details Density Functional theory(DFT) Local Density Approximation(LDA) by the general potential Linearized Augmented Plane-Wave(LAPW) method Muffin-tin radius of 2.2 a.u. the Ceperley-Alder exchange correlation potential as parametrized by Perdew and Zunger cut-off energy is 10 Ry equivalent k points of the 10 special k points in the irreducible zinc-blende Brillouin zone Density Functional theory （密度汎関数法） Local Density Approximation （局所密度近似） Linearized Augmented Plane-wave method （線形化補強平面波法） Exchange correlation potential （交換相関ポテンシャル）

Calculation results Formation energy of V Cu is low V Cu has a shallow acceptor level Defect transition energy level Formation energy of V Cu & In Cu are negative Defect formation energy vs. Fermi energy

Formation energy of a defect pair defect pair ( 欠陥対 )

Calculate results of formation energy of a defect pair A(Cu-rich, In-rich) B(Cu-poor, In-rich) C(Cu-rich, In-poor)

Summary Cu-poor, Se-rich is best for p-metal

My work Calculate chalcopyrite structure as a p-type doped superconductor material Calculate superconducting critical temperature T C Calculate band structure of CuAlS 2, chalcopyrite structure