Far-infrared spectroscopy of shallow acceptors in strained Ge/GeSi quantumwell heterostructures

Far-infrared photoconductivity spectra of strained multi-quantum well Ge/Ge 1-xSix (x approximate to 0.1) heterostructures resulting from the excitatio n of shallow accepters were investigated. The spectra are shown to be shift ed to the long-wavelength end of the far-infrared range if compared with ac cepters in bulk p-Ge due to the splitting of light and heavy holes subbands in Ge layers owing to the "built-in" deformation and size quantization. Th e shallow acceptor spectra in bulk germanium under uniaxial tension, that i s "equivalent" to the deformation of Ge layers in the heterostructures, wer e calculated by the variational technique; the results were used for the in terpretation of the experimental data. Ge/GeSi heterostructures are shown t o be a sensitive photoelectric detector for the long wavelength end of FIR range.