DOI: 

Optoelektron. napìvprovìd. teh. 61, 143-152 (2026)




M.V. Sopinskyy, K.V. Michailovska, I.Z. Indutnyi, G.P. Olkhovik. 


FEATURES OF PHOTOSTIMULATED INTERACTION IN THIN FILM STRUCTURES BASED ON COPPER AND CHALCOHENEIDE GLASSY SEMICONDUCTOR As2S3


The features of photostimulated interactions in Cu-As2S3 structures with Cu2O barrier oxide layers were studied. Films of copper and chalcogenide glassy semiconductor (ChGS) As2S3 were deposited by vacuum thermal evaporation. The Cu2O barrier layer was obtained by oxidation of the copper film in air at room temperature, which allowed preserving the photosensitive properties of the Cu-As2S3 structure a hundred times longer. The thicknesses of the films were: 150 nm (copper), 4 nm (oxide) and 110 nm (ChGS). Several series of samples were studied with similar regimes of deposition of metal and ChGS films and obtaining a barrier oxide layer. The samples were exposed to light with a wavelength of λ = 436 nm (hν = 2,84 eV), corresponding to the inter-band absorption of As2S3, and a flux density of 2·10-3 W/cm2. The expenditure of the metal film (change in its thickness Dh) both during storage in the dark, Dhd, and during irradiation, Dhl, was monitored by the change in the electrical resistance of the copper film. The processes of photostimulated and dark interactions of the Cu and As2S3 films were also monitored photometrically by measuring the specular reflection coefficient R at a wavelength of λ = 436 nm at an angle of incidence j0 = 5°.

In parallel with the kinetics of photostimulated interaction (PSI) of Cu and As2S3 films, the kinetics of their dark physicochemical interaction (DPCI) were measured. The kinetics of metal layer expenditure were also measured for the case of intermittent exposure, when intervals of photostimulated and physicochemical interactions of metal and ChGS films alternated. The mutual influence of dark and photostimulated interaction was established: an increase in the thickness of the intermediate layer of dark reaction products significantly reduces the rate of photostimulated copper transfer, while preliminary photodoping slows down the subsequent dark interaction. The results obtained indicate that the linear and quadratic stages of the DPCI kinetics describe the kinetics of the solid-phase exchange reaction with the formation of a heterogeneous layer of Cu2S + As4S4. Instead, the logarithmic kinetics of PSI is explained by the formation of a layer of ternary compounds Cu–As–S by analogy with their fusion. The reason for this difference is the different state of the As2S3 matrix during DPCI and PSI: in the first case it is in a metastable state, and in the second in a photoexcited state. The formation in the excited state of a hard photodoped layer with stronger structural connectivity, the presence of mechanical stresses and low ionic conductivity is explained by the enhanced interaction of copper ions with the electrons of lone pairs of chalcogen, in contrast to the Ag- As2S3 structures, where the interaction of the metal with the electrons of lone pairs of chalcogen is weaker, and the ionic conductivity is higher. It was found that photodoping of the As2S3 film with copper is accompanied by a decrease in the adhesion of the photodoped layer to the copper film, which can be used to form high-quality relief images without distortions associated with etching.

 

Keywords: photostimulated interaction, dark interaction, copper, As2S3, barrier layer.