Semiconductor devices employing at least one modulation doped quantum well structure and one or more etch stop layers for accurate contact formation

Abstract

A semiconductor device includes a series of layers formed on a substrate, the layers including a first plurality of layers including an n-type ohmic contact layer, a p-type modulation doped quantum well structure, an n-type modulation doped quantum well structure, and a fourth plurality of layers including a p-type ohmic contact layer. Etch stop layers are used to form contacts to the n-type ohmic contact layer and contacts to the n-type modulation doped quantum well structure. Thin capping layers are also provided to protect certain layers from oxidation. Preferably, each such etch stop layer is made sufficiently thin to permit current tunneling therethrough during operation of optoelectronic/electronic devices realized from this structure (including heterojunction thyristor devices, n-channel HFET devices, p-channel HFET devices, p-type quantum-well-base bipolar transistor devices, and n-type quantum-well-base bipolar transistor devices). In another aspect of the present invention, a high performance bipolar transistor device is realized from this structure by implanting p-type ions in a interdigitization pattern that forms a plurality of p-type ion implant regions on both sides of the p-type modulation doped quantum well structure to a depth that penetrates the n-type ohmic contact layer. The interdigitization pattern of the p-type implants reduces capacitance between the p-type modulation doped quantum well structure and the n-type ohmic contact layer to enable higher frequency operation.