Optical Detection with GaAs

amph1bius

Could anyone give me the basics in the design of an optical detector using GaAs. It's for an assignment, and heres the exact wording of the question:

Consider a GaAs quantum well. Design an optical detector whose absorption begins at a photon energy of 1.46meV. For simplicity you can assume an infinite barrier energy. You will need to look up values for the band gap, effective masses, etc.