NOVELTY - In the production of a compact n-semiconducting indium sulfide (In2S3) thin layer by atmospheric pressure chemical gas-phase vapor deposition (APCVD), an indium-containing precursor (PR(In/(g/fl))), of high vapor pressure or forming a volatile solvate, is converted into a liquid or gaseous phase then mixed with inert carrier gas (IG) and hydrogen sulfide (PR(H2S/(g))). The mixture (of H2S concentration less than 1 vol. %) is directed onto a substrate (SU) at 100-275 degrees C.    USE - The n-conducting thin layers are especially incorporated as buffer layers between the absorber and window layers in solar cells, to increase the efficiency of the cells.    ADVANTAGE - High quality, compact, homogeneous In2S3 thin layers with good substrate covering properties are obtained directly and reproducibly under atmospheric pressure and at relatively low temperature by a rapid, simple, inexpensive CVD procedure. Under the present conditions, prior art problems associated with the presence of In2S3 in the gas phase before formation of solid reaction products are avoided.    DETAILED DESCRIPTION - In the production of a compact n-semiconducting indium sulfide (In2S3) thin layer on a heated substrate, by atmospheric pressure chemical gas-phase vapor deposition (APCVD) using an indium-containing precursor, hydrogen sulfide (H2S) as reactive gaseous precursor and an inert carrier gas stream (IG), an indium-containing precursor (PR(In/(g/fl))) (having a high vapor pressure or forming a volatile adduct with a solvent) is converted into a liquid or gaseous phase, then mixed with the inert gas stream and H2S (PR(H2S/(g))) in amounts such that the absolute H2S concentration in the mixing zone is 1 vol. % or less and the indium concentration ensures a compact layer. The mixture is directed onto the substrate (SU), which is heated to 100-275 degrees C.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of a batch process for producing a compact, thin n-semiconducting indium sulfide layer by atmospheric pressure chemical gas-phase vapor deposition (APCVD). (Drawing includes non-English language text).    APCVD reactor (APCVD-R)    Dosing valve (DV)    Hydrogen sulfide gas, as first precursor (PR(H2S/(g)))    Indium-containing second precursor (PR(In/(g/fl)))    Gas (g)    Liquid (fl)    Solid (f)    Inert gas stream (IG)    Precursor mixture (MPR)    Mixing zone (MP)    Ambient pressure (RPR)    Ambient pressure (RTE)    Substrate (SU)    Temperature (T)    Reaction zone (RP)    Non-deposited reaction product (UPR)