Authors: P N Vinod
Publish Date: 2007/03/24
Volume: 18, Issue: 8, Pages: 805-810
Abstract
The establishment of a suitable contact formation methodology is a critical part of the technological development of any metaltosemiconductor contact structure Many test structures and methodologies have been proposed to estimate the specific contact resistance ρc of the planar ohmic contacts formed on the heavily doped semiconductor surface These test structures are usually processed on the same wafer to monitor a particular process In this study new experimental procedure has been evolved to assess the value of ρc of the screenprinted front silver Ag thickfilm metal contact to the silicon surface The essential feature of this methodology is that it is an iteration technique based on the calculation of power loss associated with various resistive components of the solar cell normalized to the unit cell area Therefore this method avoids the complexity of making the design of any lay out of a standard contact resistance test structure like transmission line model TLM or Kelvin resistor etc It was shown that value of specific contact resistance of the order of 10 × 10−5 Ω−cm 2 is measured for the Ag metal contacts formed on the n+ silicon surface This value is much lower than the ρc data previously reported for the screenprinted Ag contacts The sintering process of the front metal contact structure at different furnace setting is carried out to understand the possible wet interaction and metal contact formation as a function of the firing Therefore the study is further extended to study the peak firing temperature dependence of the ρc of screenprinted Ag metal contacts It will help to assess the specific contact resistance of the ohmic contacts as a function of firing temperature of sintering process
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