Composition dependent doping and transport properties of CuGaSe2

ABSTRACTChalcopyrites are doped by intrinsic defects, therefore their doping behavior depends on their composition. The doping and transport properties of epitaxial CuGaSe2 layers prepared under varying Cu excess have been investigated by temperature dependent Hall effect and conductivity measurements. Two acceptors, 134 meV and 80 meV deep, and a high degree of compensation, increasing with decreasing Cu excess, are found. The temperature dependence of the mobility indicates scattering with phonons, demonstrating high quality material. Defect scattering dominates at lower temperatures for CuGaSe2 grown under moderate Cu excess. CuGaSe2 grown under little or no Cu excess shows transport in a defect band at lower temperatures.