Shallow acceptors in strained Ge/Ge1-xSix heterostructures with quantum wells

The energies of localized acceptor states in quantum wells (strained Ge lay ers in Ge/Ge1 - xSix heterostructures) were analyzed theoretically in relat ion to the quantum well width and the impurity position in the well. The im purity absorption spectrum in the far IR range is calculated. Comparison of the results of the calculation with experimental photoconductivity spectra allows an estimation of the acceptor distribution in the quantum well to b e made. In particular, it was concluded that acceptors may largely concentr ate near the heterointerfaces. The absorption spectrum is calculated taking into account the resonance impurity states. This allows the features obser ved in the short-wavelength region of the spectrum to be interpreted as bei ng due to transitions into the resonance energy levels "linked" to the uppe r size-quantization subbands. (C) 2000 MAIK "Nauka/Interperiodica".