Design and optimization of a dual band uncold quantum well photodetector based on GaN/Al0.22Ga0.78N with maximum detectivity at wavelengths 325 and 353 nm

We report the result of the design and optimization of a dualband uncold quantum well photo detector based on GaN/Al0.22Ga0.78N with maximum directivity at wave lengths325 nanometer (photoconductive mode) and 353 nanometer(tunneling mode) at room temperature. Introduction of quantum well in to the active region of devices is expected to enhancethe quantum efficiency due to the high absorption coefficient.The designed detector has three periodic well. The cut off wave length of the quantum well photo detector can be tuned byadjusting the well width, well composition and barrier height.According to the result of calculations the well width, thebarrier width and amount of x are 43 A, 11A0 and 0.22 respectively. To improve the functions of detector, we chose the amount of the doping about 3×10 ^18cm^-3 . The maximum responsively in the photoconductive mode is 0.7A / W . Thepeak responsively increased with decreasing barrier thickness toenhanced tunneling of photo generated carriers as for tunnelingmode is 0.23A / W . Also the maximum specific directivity in the photoconductive mode and in the tunneling mode are1.8 ×10^14 cmHz / W ^1/ 2 and 1 10 cmHz /W 14 1/ 2 / W respectively.