Epitaxial photosensitive Pb_(1-x)Sn_xSe(In)/PbSe_(1-x)S_x heterojunctions obtained in the ultrahigh vacuum

摘要

Photosensitive isoperiodical heterojunctions (HJ) Pb_(1-x)Sn_xSe(In)/PbSe_(1-x)S_x were obtained in the ultrahigh vacuum ( ≤ 3/5 · 10~(-7)Pa) at quasi-equilibrium conditions by the method of the "hot wall" in the unified technological cycle on substrates BaF_2. In structural relation HJ components are ideally coordinated pair for the epitaxy. Volt-ampere and spectral characteristics of the HJ were recorded. Straight branch of the volt-ampere characteristics satisfies to the exponential law J=J_0exp (eU/βκT) at small displacements. At 77 K the coefficient β changes in the interval 1.5/2 that is typical for the generation-recombination mechanism of the current leakage through the region of the space charge. Maximum photosensitivity was observed at λ_(MAX)=12.0 μm. The increase of the temperature of the HJ manufacture leads to the shift of the photosensitivity maximum to the short-wave region, that is explained by the noticeable tin diffusion from the ground layer to the growing layer and as a result the HJ acquires characteristics of the varyzone structure.