Anisotropic hole-mass tensor of CuIn1-xGax(S,Se)2:: Presence of free carriers narrows the energy gap

Analysis of the band edges of CuIn(1-x)Ga(x) (S, Se)(2) with x= 0.0, 0.5, and 1.0 reveals that (i) CuIn(1-x)Ga(x)S(2) has larger effective electron m(c) and hole m(v) masses than CuIn(1-x)Ga(x)Se(2); (ii) whereas Ga content affects band curvatures only slightly, the sign of the crystal- field split Delta(cf) as well as the spin-orbit coupling affect my strongly; (iii) the optical response epsilon(2) (h omega) is comparable for all six compounds; and (iv) band filling of electrons (n= 10(19) cm(-3)) and holes (p=n) narrows the band gap by E(g) approximate to E(g)(0)- 0.1 eV and generates an optical band gap of E(g)(opt) approximate to E(g)+ 0.2 eV. (C) 2008 American Institute of Physics.