NOVELTY - Thermal evaporation apparatus comprises an emission-reducing layer (6) arranged such that an external surface of a vapor outlet (3) of a vapor-receiving pipe (4) directed to a substrate (5) exhibits low emission. At least the surfaces of a melting crucible (1), vapor-receiving pipe and emission-reducing layer and an outer surface of a pipe heater (7) contacting the material vapor are of corrosion-resistant material. The corrosion-resistant material includes quartz, fused silica, ceramic, graphite, or carbon fiber-reinforced carbon (CFC).    USE - For depositing selenium on a substrate or for depositing a layer onto a CIS precursor layer in manufacturing a photovoltaic cell, particularly a copper indium diselenide (CIS) solar module (claimed).    ADVANTAGE - The thermal evaporation apparatus can be operated at high temperatures at greater than or equal to400degreesC to achieve high deposition rates. It is resistant to wear even at high temperatures and in the presence of aggressive materials, e.g. selenium. The emission-reducing layer reduces the thermal emission of the vapor outlet at least in a direction towards the substrate so that heating of substrate by radiation from the vapor outlet is reduced to an acceptable level and that the material reaching the substrate is not re-vaporized from the surface of the substrate, even if the vapor outlet is operated at high temperatures, e.g. greater than or equal to350degreesC.    DETAILED DESCRIPTION - Thermal evaporation apparatus comprises a melting crucible for receiving material to be deposited. An electric heater (2) heats the material in the crucible to generate vapor. A vapor outlet comprises a vapor-receiving pipe having vapor outlet passages (4b). An emission-reducing layer is arranged such that an external surface of the vapor outlet directed to the substrate exhibits low emission. At least the surfaces of the crucible, vapor-receiving pipe and emission-reducing layer contacting the material vapor are of corrosion-resistant material. A line-shaped pipe heater in the interior of the vapor outlet extends along or in parallel with a longitudinal axis of the vapor receiving pipe. The pipe heater has an outer corrosion-resistant surface contacting with the material vapor and formed of a corrosion-resistant material. The corrosion-resistant material includes quartz, fused silica, ceramic, graphite, or carbon fiber-reinforced carbon (CFC). An INDEPENDENT CLAIM is included for a method of depositing a material onto a substrate by thermal evaporation.    DESCRIPTION OF DRAWING(S) - The figure shows a thermal vapor deposition apparatus.    Melting crucible (1)    Electric heater (2)    Vapor outlet (3)    Vapor-receiving pipe (4)    End (4a)    Vapor outlet passages (4b)    Substrate (5)    Emission-reducing layer (6)    Vapor passage through holes (6a)    Pipe heater (7)    Heater (7a)    Bulb (7b)    Electrical connectors (7d)    Valve (9)