A design strategy for achieving more than 90% of the overlap integral of electron and hole wavefunctions in high-AlN-mole-fraction AlxGa1%xN multiple quantum wells

A strategy for increasing the square of an overlap integral of electron and hole wavefunctions (I 2) in polar c-plane AlxGa1%xN multiple quantum wells (MQWs) is proposed. By applying quadratic modulation to AlN mole fractions along the c-axis, local bandgap energies and concentrations of immobile charges induced by polarization discontinuity are simultaneously controlled throughout the MQW structure, and optimized band profiles are eventually achieved. The I 2 value can be substantially increased to 94% when the well width (Lw) is smaller than 4.0 nm. In addition, I 2 greater than 80% is predicted even for thick MQWs with Lw of 10 nm.