Garrett approximation for asymmetric rectangular potentials and its applications to quantum well infrared photodetectors

Garrett’s approximation for the calculation of bound states energy in square wells is applied in a consistent way. So, one obtains simple formulas for these energies, with errors of about 1% for moderate, and 0.01% for deep wells. The application in of our results in the physics of quantum well infrared photodetectors is briefly discussed.