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Large-Area PECVD System for 30×30 cm² Substrates

The large-area plasma-enhanced chemical vapour deposition (PECVD) system provides reproducible base-line processes for single- and multi-junction layer stack solar cells (1 cm2) and modules (676 cm2) of hydrogenated amorphous and microcrystalline silicon with integrated n- and p-type doped silicon oxygen alloys as intermediate and back reflectors. These thin film silicon based solar cells can be used to verify and examine the influence of changes in the cell process or other components. The PECVD system is thus integrated in the further development of new prototype devices on advanced textured glass substrates fabricated by nano-imprinting and ion-beam etching of mask for optimized light management in photovoltaic devices. Evaluation of transparent conductive oxide (TCO) films serving as a front contact, back reflectors and other components of the solar cell can be performed. In a close cooperation with the Laser Process and Module Technology Group different interconnection concepts for fabrication of high efficient solar modules with aperture are of 676 cm2 are developed.

Technical Equipment

The large-area PECVD system consists of one load chamber and three deposition chambers – one for p- or n-doped silicon films and two other chambers are used preparation of intrinsic hydrogenated amorphous (a-Si:H) and microcrystalline (µc-Si:H) absorber layers. The layers can be grown with various compositions of process gases and plasma excitation frequency of 13.56 MHz, allowing a wide range of thin film materials to be produced.

Additionally, doped silicon-oxygen alloy (a/µc-SiOx:H) layers with special functions, such as intermediate and back reflectors or window layers with an improved light coupling are being developed. The basic version of the large-area PECVD system was supplied by MRG Inc. (Colorado, USA). The system was further equipped and optimized at IEK-5 Photovoltaics. The PECVD electrodes with showerhead configuration were developed within the framework of a cooperation between FAP GmbH (Dresden, Germany) and IEK-5. The electrodes can be operated at RF frequencies (13.56 MHz). The maximum base pressure of the system is 1×10-8 mbar and temperature is ~200 °C.

BauelemEntw04PECVD system for 30×30cm2 substrates. The system aims at the fabrication of tandem solar cells composed of a-Si:H and µc-Si:H and at their integration in solar modules.


Joachim Kirchhoff
Dr. Tsvetelina Merdzhanova