Absorption in GaAs/${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$As quantum wells with resonant barriers for improved responsivity

We have devised a modified GaAs quantum-well structure with high responsivity. The modification includes putting small barriers on the sides of the quantum well to increase absorption from the bound to an extended state, thus optimizing device performance by increasing the amplitude of the extended-state wave function in the well region. The width and the height of the barriers can be modified to control the spectrum of absorption. The analysis was done using a two-band tight-binding method to calculate the wave functions. The results indicate that, in general, the bigger and the wider the barriers, the narrower and the larger the absorption is, and the stronger the resonance becomes.