Stability and electronic structures of CuxTe

In this work, the authors study the stability and electronic properties of CuxTe as a function of the Cu/Te ratio using first-principles calculations. They find that CuxTe shows bistability with energy minimum at x approximate to 1.25 and x approximate to 1.75. At low x, CuxTe is more stable in the tetragonal-based structures, whereas for x > 1.47, it is more stable in the trigonal-based structures. The valence-band maximum of Cu2Te is found to be 0.7 eV higher than that of CdTe, indicating that it can easily be doped p type. The Cu diffusion barriers and hole density decrease with increasing Cu concentration, indicating that for x similar to 2, ionic conductivity may play a role. (c) 2007 American Institute of Physics.