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 (I2) 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 I2 value can be substantially increased to 94% when the well width (Lw) is smaller than 4.0 nm. In addition, I2 greater than 80% is predicted even for thick MQWs with Lw of 10 nm.