SEMICONDUCTOR DEVICES EMPLOYING AT LEAST ONE MODULATION DOPED QUANTUM WELL STRUCTURE AND ONE OR MORE ETCH STOP LAYERS FOR ACCURATE CONTACT FORMATION AND FABRICATION METHODOLOGY OF SAME

摘要

A semiconductor device includes a series of layers formed on a substrate (10), the layers including a first plurality of layers including an n-type ohmic contact layer (14), a p-type modulation doped quantum well structure (20), an n-type modulation doped quantum well structure (24), and a fourth plurality of layers including a p-type ohmic contact layer (30). Etch stop layers (16 and 28a) 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).