Self assembled nanoparticle Pb 1−xFe xSe/single crystal Si heterojunctions

Abstract

Nanoparticle Pb 1− x Fe x Se (0.00 ⩽ x ⩽ 0.16) thin films have been deposited on quartz, glass and silicon substrates by chemical bath deposition technique. Structural and optical properties of the films with iron concentration 0.00 ⩽ x ⩽ 0.16 indicate that the films grow as single-phase Pb 1− x Fe x Se ternary alloys with rocksalt structure and with direct optical band gaps ( E g) that increase with decrease in grain size and have values larger than 0.28 eV of the bulk PbSe. Average grain size in films grown at fixed bath temperature T b of 85 °C is observed to decrease from 72 to 22 nm whereas lattice parameter is observed to increase from 6.12 to 6.14 Å with increase in Fe concentration from x = 0.00 to x = 0.16. The observed blue shift in film materials originates from quantum confinement in the nanograins. Nanoparticle Pb 1− x Fe x Se/single crystal Si heterojunctions show rectifying behavior. On illumination of heterojunctions with visible light current is observed to increase in forward and reverse bias. This increase in current in the presence of visible light is considered to be due to carrier multiplication by Auger electron emission.