Quantum wells are fabricated by placing a thin layer of a smaller band gap semiconductor (well) between two thick layers of a larger band gap semiconductor (barrier). The band gaps align yielding a one-dimensional square well potential for an electron. Through this project, reflectivity and photoluminescence (emission from the sample following excitation) measurements are performed on five different single quantum wells and a pair of double quantum wells (two wells separated by a thin barrier) which yields the energy levels of the electron and thus demonstrates the formation of discrete states in square wells, the dependence on barrier height and well widths, and the formation of symmetric and antisymmetric states due to tunneling and overlap in double quantum wells. Lifetime measurements are performed by time-resolved photoluminescence on doping superlattices (semiconductor with alternate regions of n- and p- type doping). These experiments can modernize any undergraduate curriculum and may be treated as experiments in modern physics and quantum mechanics. They are timely and relate to current technology and research. The semiconductor heterostructures are applied as tunable quantum well lasers and light-emitting diodes.
