NOVELTY - A method (M1) for recovering and recycling silane or silane/hydrogen mixtures from deposition chamber (C1) used in a silicon layer deposition process, involves identifying time periods during the deposition process when only excess silane or silane/hydrogen mixtures are exiting from (C1); collecting the silane or silane/hydrogen mixture; and recycling the collected silane or silane/hydrogen mixture to (C1).    USE - In the production of thin film silicon layers, particularly for manufacturing a solar cell (claimed).    ADVANTAGE - The method provides safe recovery and recycle of 5-80% of unreacted silane or silane/hydrogen mixture, thus reducing production costs of solar cells with low maintenance and providing improved quality of solar cells. The method and apparatus rely on specific time periods during the deposition process when only silane or silane/hydrogen mixtures are flowing through (C1). During these times, no additional gas, such as boron, phosphorus or carbon containing gases are flowing or present in (C1). Therefore during these time periods, the silane is directed to a collection vessel rather than to the normal waste destruction unit.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) system for deposition of silicon layer comprising (C1), substrate held in (C1), source of silane in communication with (C1), an energy source (E1) associated with (C1) for activating silane to deposit silicon layer onto the substrate, collection unit communicating with (C1) for collecting excess silane exiting (C1) and for recycling collected silane to (C1); and    (2) method (M2) of depositing silicon layer on a substrate in (C1) involving during first portions of deposition cycle providing a source of silane to (C1) to deposit silicon layer on the substrate; during second portions of deposition cycle a source of silane mixed with at least one gas to (C1) to deposit mixed silicon layer on the substrate; sending excess gas exiting (C1) during the second portions of the deposition cycle to waste disposal unit; collecting excess silane exiting (C1) during the first portions of the deposition cycle, and recycling the collected silane to (C1).    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a multi chamber plasma enhanced chemical vapor deposition (PECVD) system.    Multiple chamber PECVD system (100)    Multiple deposition chambers (120)    Deposition gas source (130)    Standard waste treatment unit (140)    Collection unit (150)