Abstract:
Long wavelength Si<SUB>1-X</SUB>Ge<SUB>X</SUB>/Si heterojunction internal photoemission (HIP) infrared detectors have been successfully demonstrated utilizing the growth of degenerately boron doped Si<SUB>1-X</SUB>Ge<SUB>X</SUB> layers on Si. Recently, Si<SUB>0.7</SUB>GE<SUB>0.3</SUB>/SI HIP detectors with either a Si<SUB>1-X</SUB>Ge<SUB>X</SUB> single layer or a Si<SUB>1-X</SUB>Ge<SUB>X</SUB>/Si multilayer have been demonstrated with cutoff wavelengths out to 23 µm. Near-ideal thermionic emission dark current characteristics were measured and the electrical potential barriers were determined by the Richardson plot. A photoresponse model, similar to the modified Fowler Equation has been developed for the Si<SUB>1-X</SUB>Ge<SUB>X</SUB>/Si heterojunction internal photoemission infrared detector at wavelengths corresponding to photon energies less than the Fermi energy. The optical potential barriers, the corresponding cutoff wavelengths, and the emission coefficients, C<SUB>1</SUB>, for the HIP detectors have been determined from the measured spectral responses using the photoresponse model. Similar optical and thermal potential barriers were obtained.
