Negative resistance semiconductor device

Abstract

A semiconductor device having a superlattice structure, which comprises at least one unit structure including first and third semiconductor layers as quantum well layers, and a second semiconductor layer as a barrier layer, which are arranged alternately on each other is described. The first semiconductor layer has a higher impurity concentration than the third semiconductor layer and has a quantum energy level determined by its thickness. The third semiconductor layer is of a thickness having quantum energy levels, one of which is lower than that of the first semiconductor layer and the second of which is equal to or higher than that of the first semiconductor layer. The second semiconductor layer is of a thickness which allows electrons existing at the second quantum energy level of the third semiconductor layer to transfer easily from the third to the first semiconductor layer. An increase in voltage applied to the semiconductor device causes electrons to transfer to the first semiconductor layer through the second quantum energy level of the third semiconductor layer to reduce the mobility of electrons in the first semiconductor layer, thus causing the semiconductor device to develop a negative resistance.