Effective Mass Effects in Triangular Quantum Wells Achieved From Compositional Grading

The energy levels of a triangular quantum well whose structure is obtained from variations in alloy composition is studied theoretically. Various approximation schemes are utilized to determine the energy levels of the conduction and valence bands ranging from a mean effective mass in the well to a model in which the triangular well is composed of flat layers with varying effective masses. It is found that the absolute positions of the energy levels is a strong function of the number of layers used to form the triangular well, whereas the energy difference between the ground and first excited intraband states is insensitive to the number of layers. In contrast, the interband transitions are strongly dependent upon the number of layers used to obtain the grading.