BAND STRUCTURES AND PRESSURE-DEPENDENCE OF THE BAND-GAPS OF GAN

The linear muffin-tin orbital method is used with the atomic-sphere approximation to study the ground-state properties, band structures and pressure dependence of the band gaps of zincblende GaN. The equilibrium lattice constant calculated is smaller than the experimental value by about 2%. It is found that the fundamental band gap is direct from GAMMA15v to GAMMA1c and that the value (3.90 eV) is in good agreement with the experimental value. The linear pressure coefficient for this band gap is much smaller than those for GaAs and GaP. The total density of states and local density of states are discussed. Moreover, the band structure of wurtzite GaN is also studied. It is found that the band gap of wurtzite GaN is smaller than that of zincblende GaN, which agrees well with the experimental results.