Fracture of AlxGa1-xN/GaN heterostructure - Compositional and impurity dependence

Grown-in stress and subsequent fracture in AlxGa1-xN/GaN heterostructures w ith or without impurity doping were studied in situ. It was found that the critical thickness of AlxGa1-xN depends not only on its composition but als o on the concentration of impurities such as Si or Mg. Increase in tensile stress during growth at a constant AIN molar fraction can be explained by t he increase in the biaxial modulus of AlxGa1-xN due to impurity doping.