Influence of Polysilicon Thickness on Properties of Screen‐Printed Silver Paste Metallized Silicon Oxide/Polysilicon Passivated Contacts

This work investigates how the thickness of the polysilicon layer and temperatures during contact sintering influence the properties of SiOx/polysilicon passivated contacts. The n+ polysilicon layers deposited by low‐pressure chemical vapor deposition (LPCVD) on top of a thin wet chemically grown interface oxide layer providing chemical and field‐effect passivation on n‐type monocrystalline silicon wafers are investigated. Three different polysilicon layer thicknesses of 50, 100, and 150 nm are considered in this work. A high level of passivation with implied Voc values above 735 mV and J01 below 5 fA cm−2 is obtained for symmetric lifetime test samples. These samples are used to investigate the interaction of the silver paste with the polysilicon layer at different fast firing peak temperatures. Reduction in polysilicon layer thickness leads to an increase in contact resistivity as well as in J0met. Excellent J0met values of the order of J01 with contact resistivity values below 2 mΩ cm2 are obtained for samples with polysilicon layers of 100 and 150 nm thickness. In this work, the authors present how the thickness of the polysilicon layer and the peak fast firing temperature influence the contact. For this purpose, the authors present photoluminescence and scanning electron microscope (SEM) images to visualize the contact formation. They also try to relate the size of silver crystallites determined from SEM images, to the contact properties.