A NEW MODULAR MULTICHAMBER PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION SYSTEM

The present work reports on a new modular UHV multichamber PECVD syste m with characteristics which prevent both the incorporation of residua l impurities and cross contamination between different layers. A wide range of intrinsic and doped hydrogenated amorphous silicon (a-Si:H) m aterials have been produced and single junction pin solar cells with a n efficiency greater than 10% have been readily obtained with little o ptimization. The system contains three UHV modular process zones (MPZ' s); the MPZ's and a load lock chamber are located around a central iso lation and transfer zone which contains the transport mechanism consis ting of an arm with radial and linear movement. This configuration all ows for introduction of the substrate into the MPZ's in any sequence s o that any type of multilayer device can be produced. The interelectro de distance in the MPZ's can be adjusted between 1 and 5 cm. This has been found to be an important parameter in the optimisation of the dep osition rate and of the uniformity. The multichamber concept also allo ws individually optimized deposition temperatures and interelectrode d istances for the various layers. The system installed in Utrecht will be employed for further optimization of single junction solar cells an d for research and development of stable a-Si:H tandem cells.