A method for vapor deposition of a sublimated source material, such as CdTe, onto substrates in a continuous, non-stop manner through the apparatus is provided. The sublimated source material moves through a distribution plate and deposits onto the upper surface of the substrates as they are conveyed through the deposition area. The substrates move into and out of the deposition area through entry and exit slots that are defined by transversely extending entrance and exit seals. The seals are disposed at a gap distance above the upper surface of the substrates that is less than the distance or spacing between the upper surface of the substrates and the distribution plate. The seals have a ratio of longitudinal length (in the direction of conveyance of the substrates) to gap distance of from about 10:1 to about 100:1.