Effect of Asymmetric Well Quantum Dots-in-a-well Infrared Photodetectors on Density of States Using NEGF Formalism

Local Density of State (LDOS) and hence Density of State (DOS) at different energy levels of asymmetric conical shaped InAs/InGaAs quantum dots-in-a-well (DWELL) infrared photo-detector has been calculated through Non-Equilibrium Green's Function (NEGF) approach to explain the tri-band operation. Method of finite difference is used to solve the kinetic equation of Green's function and Self-energy is calculated in a recursive manner. Monotonic red shift of spectral response with incremental quantum well width is observed in terms of energy level difference, which is found in good agreement with previously reported experimental data, and the wavelengths corresponding to the peaks of responsivity is estimated from the DOS profile. Relative effect of changing the bottom quantum well width on ground and other higher state energy levels are also reported.