Elasticity and polarization of GaxAl1-xN alloys subjected to uniaxial and biaxial compression

摘要

Elasticity and polarization of GaxAl1-xN alloys subjected to uniaxial and homogeneous biaxial compression are calculated using first-principles methods. The uniaxial compression along the c-axis reduces Young's modulus along the c-axis, and enhances bulk modulus and total polarization, whereas the biaxial compression in the plane perpendicular to the c-axis enhances bulk and Young's moduli. It is also found that when the in-plane biaxial compression is applied by constraining the a-axis lattice constant to that of AlN, the bulk and Young's moduli dramatically increase with increasing Ga concentration, and the total polarization could be suppressed, even annihilated,and finally enhanced by controlling Ga concentration.