Electronic bandstructure of the ZnTe absorber material

Due to its large absorption coefficient, zinc telluride proved to be useful for the production of high-efficiency multi-junction solar cells. Nowadays ZnTe with a mixture of zincblende and wurtzite phases is fabricated by thin film growth techniques. The optical properties of both phases have been extensively studied by ab initio density functional methods [1]. Here we focus on the question whether the effective electron and hole mass in ZnTe are small enough to meet the high-efficiency expectation of the ZnTe absorber material in solar cells and present direction dependent effective mass and Luttinger and Luttinger-like parameters of cubic and wurtzite ZnTe, respectively. Making use of the transferability of ionic model potential parameters [2] and the experimentally known transition energies of different II-VI compounds ZnX (X=O, S, Se, Te), we obtained one single set of cationic model parameters for the Zn atom. The calculations have been performed by means of the empirical pseudopotential method using a simple empty core model potential.
[1] S. Zh. Krazhanov, P. Ravindran, A. Kjekshus, H. Fjellvag, and B.G. Svensson, Phys. Rev. B 75, 155104 (2007).
[2] D. Fritsch, H. Schmidt, M. Grundmann, Appl. Phys. Lett. 88, 124104 (2006), Phys. Rev. B 69, 165204 (2004).