Long wavelength infrared photocurrent study of Si-SiGe heterostructures

We report on an experimental long wavelength infrared photocurrent study of a series of a Si-SiGe double-heterostructure samples. The active region is a thin heavily p-type doped SiGe layer, and the photoexcited holes due to free-carrier absorption are collected over the potential barrier resulting from the Si-SiGe valence-band offset. Photocurrent spectra with different cutoff wavelengths are observed for samples with different SiGe compositions, arising from internal photoemission in the Si-SiGe heterojunction. Photocurrents at finite biases and at zero bias (i.e., photovoltaic operation) are studied. Optimizing device parameters may lead to detector structures for large focal plane arrays.

Long wavelength infrared photocurrent study of Si-SiGe heterostructures Journal Articles