SILICON-BASED SEMICONDUCTOR HETEROSTRUCTURES - COLUMN-IV BANDGAP ENGINEERING

Semiconductor heterostructures greatly enhance the range of possible device configurations and open the door to new physical phenomena such as tunneling, tunable optical absorption, real space carrier transfer, two-dimensional carrier gases, and quantum size effects. Because silicon had no natural semiconductor partner, exploitation of these effects had been confined to compound semiconductors. By use of strained layer epitaxy, we have now learned how to grow high quality GexSi1-x/Si heterostructures and have applied these materials to a wide range of heterostructure devices. This paper reviews the mechanisms of strained layer growth, the bandstructure of the resulting material, and its use in test devices, including superlattice avalanche photodiodes for fiber optic communication, intra-subband optical detectors and arrays operating in the 10-15-mu-m wavelength range, mobility enhanced modulation-doped transistors, heterojunction bipolar transistors with cut off frequencies of 75 GHz, and negative resistance devices based on resonant tunneling and real space carrier transfer.