Method for continuously producing tandem amorphous photovoltaic cells

A method of continuously producing tandem, amorphous photovoltaic cells on an elongated web of substrate material which is adapted to continuously move from a pay-off mandril through a substrate cleaning chamber and a series of at least two triads of isolated deposition chambers to a take-up mandril;

• sources of reaction gases including at least precursor semiconductor material;
• means for introducing reaction gas mixtures into each deposition chamber for disassociation and deposition of successive noncrystalline semiconductor layers of varying conductivity onto the web of substrate material passing therethrough;
• the method comprising the steps of:
• automatically threading the web of substrate material so as to deliver and secure the leading edge thereof from the pay-off mandril to the take-up mandril;
• attaching the leading edge of replacement interleaf sheeting from a replacement interleaf core to the substrate material prior to winding the substrate material about the take-up mandril, whereby the interleaf sheeting is positioned between adjacent layers of substrate material as the substrate material is wound about the take-up mandril;
• sealing and vacuumizing the chambers through which the substrate material passes;
• flushing the chambers;
• heating the deposition chambers to warm the substrate material and the reaction gas mixtures to deposition temperatures;
• providing a gas gate between each pair of adjacent deposition chambers of each triad;
• providing a source of sweep gas;
• introducing the sweep gas into each of the gas gates;
• providing sources of reaction gases;
• setting mixtures of reaction gases and introducing the preset reaction gas mixtures into the deposition chambers, the flow of reaction gas mixtures and the flow of sweep gas adapted to substantially prevent cross-contaminating of the process gas mixtures in adjacent deposition chambers;
• providing sources of cleansing gases;
• setting a flow of cleansing gases into a substrate cleaning chamber;
• the step of setting and introducing the reaction gas mixtures further comprising:
• (1) setting a flow of semiconductor precursor gases and a dopant gas from the sources into the first deposition chamber of each triad;
• (2) setting a flow of semiconductor precursor gases and a dopant gas of opposite conductivity from the sources into the third deposition chamber of each triad;
• and (3) setting a flow of semiconductor precursor gases into the second deposition chamber of each triad;
• providing sources of isolation gases;
• providing a discrete isolation chamber between the third deposition chamber of the first triad and the first deposition chamber of the second triad;
• setting an isolation gas mixture from the sources and introducing the preset isolation gas mixture into the discrete isolation chamber;
• directing the isolation gas mixture to unidirectionally flow from the discrete isolation chamber into the third chamber of the first triad and the first chamber of the second triad;
• energizing the means for disassociating and depositing the reaction gas mixtures onto the substrate material;
• starting the means for continuously moving the substrate material through the deposition chambers;
• and
• substantially maintaining the preset substrate temperature, speed of substrate travel, substrate tension, mixtures of reaction gases in each deposition chamber, mixtures of isolation gases in the isolation chamber, sweep gas in the gas gates, pressure differentials between adjacent chambers, and vacuum pressures;
• whereby, high quality tandem photovoltaic cells may be continuously produced.