Effects of numbers of wells on optical properties of periodic InGaN graded structure

The optical properties of periodic graded GaN/InGaN are studied. We have designed graded InGaN quantum well (QW) structures with the indium composition increasing then decreasing in a zigzag pattern. Through polarization doping, this naturally creates alternating p-type and n-type regions. Separate structures are designed by varying the number of repeating periods (1 to 3), while maintaining constant overall structure thicknesses. Calculation of the transition probabilities and the electron and hole wave-functions between the conduction band and the valence band reveals a complex energy structure which predicts the photoluminescence peaks for band to band transitions.