Abstract: A semiconductor apparatus is provided. The apparatus has a multiple layer heterostructure having first and second material layers having first and second bandgaps, respectively and a semiconductor layer of a third bandgap being fabricated between said material layers, the bottom of the conduction band of said semiconductor layer is below the bottom of the conduction band of said material layers, and the top of the valence band of said semiconductor layer is above the top of the valence band of said material layers, the thickness of said semiconductor layer is chosen sufficient for carrier confinement effects within said semiconductor layer to influence the optical properties of said multiple layer heterostructure, and means for applying an electric field to the multiple layer heterostructure in order to vary an optical absorption coefficient and an index of refraction of the multiple layer heterostructure in response to the electric field.

Abstract: A control circuit for a multi-denomination cash dispenser in which the number of bills or coins of each denomination, for varying desired quantities of money to be dispensed, are selected such that the total amount of time required to dispense varying quantities of each denomination is minimized. The control circuit of this invention does not necessarily result in dispensing of cash with a minimum number of bills and/or coins. However, it does, in addition to minimizing the cycle time of the cash dispensing operation, equalize the wear on the various individual dispensers; deplete the inventories of different denominations at approximately the same rate, thereby avoiding premature depletion of one denomination relative to the others, and provide the user with a varied mix of denominations regardless of the amount of currency requested.