Polycrystalline films of ZnS with a slight excess of S have been grown on (100) Si by congruent sublimation from a single Knudsen cell. Intense blue emission is observed at 460 nm from room-temperature photoluminescence studies, and is ascribed to S-Zn vacancies acting as self-activated (SA) centres. The emission is quenched by the addition of Zn from a second Knudsen cell, which also causes the growth of a luminescent peak centred on 678 nm. No reduction in the SA luminescence is seen when co-sublimating ZnS and AgS. implying that it is not possible to remove the S-vacancy completely. Quenching of the blue emission occurs when Mn, instead of Zn, is added to the ZnS films, providing direct evidence of M n incorporation into Zn vacancies. At the optimum M n concentration, the intensity of t h e Mn emission at 580 nm is comparable to t h e blue emission (460 nm) from the undoped ZnS films.
Origin of green luminescence in ZnO thin film grown by molecular-beam epitaxy J. Appl. Phys. 98, 073502 (2005); 10.1063/1.2064308 Photoemission study of Cu deposition on molecular-beam-epitaxy-grown ZnS(001) J. Appl. Phys. 95, 743 (2004); 10.1063/1.1635969
Conductance technique measurements of the density of states between Si and ZnS grown by molecular beam epitaxyThin films of ZnS, with varying concentrations of Zn, have been grown onto p--Si using the molecular beam deposition method. By increasing the Zn content, a rise in the conductivity is seen and a peak is achieved. With too much Zn, however, the conductivity reduces quickly. The most conducting film forms an ohmic contact with thep--Si substrate. Calculation of the Fermi energy in this device shows that the Fermi level lies at 0.11 eV below the conduction band. The less conducting material is found to form a pseudoschottky barrier at the p--Si interface. The conduction process is thought to occur due to an excess of S vacancies (donor sites) compared to Zn vacancies (acceptor sites). The addition of Zn seems to reduce the effect of autocompensation, usually a hindrance in the fabrication of conducting ZnS films.
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