Semiconductor device for detecting electromagnetic radiation or particles

Abstract

A semiconductor device of the doping superlattice type for detecting electromagnetic radiation or particles comprises a semi-insulating substrate (10), a first layer (11) of either n-type or p-type conductivity deposited thereon, a plurality of layers (12, 13, 14) of alternating conductivity types deposited in series on said first layer (11), a strongly p-type electrode region which extends through said p-type and n-type layers (11, 12, 13, 14) and defines a first selective electrode (15), and a strongly n-type electrode region which also extends through said p-type and n-type layers (11, 12, 13, 14), and which is spaced apart from said strongly p-type region and defines a second selective electrode. The device is a homogeneous semiconductor in which the n-type and p-type layers other than the first layer (11) and the outermost layer (14)have substantially identical thicknesses and doping concentrations. The first layer (11) and the outermost layer (14) are of the same conductivity type and have a thickness substantially equal to one half of the thickness of each of the other layers (12, 13). Furthermore, the first layer and the outermost layer have a doping concentration substantially identical to the doping concentration of the other layers. This makes it possible to completely deplete the entire structure thus a high reverse bias can be applied to the device thereby tilting the resultant electric field with respect to the layers. A device of this kind is particularly suited for use as an optical detector in the infrared wavelength region around 1 .mu.m and longer. The device has low dark current at room temperature, a very small capacitance and therefore a fast response time.