Resistance analysis of wrapped through emitters

To analyze the via-hole emitter resistance two different test devices were designed consisting of symmetric n(+)pn(+)-structures whereas the emitter via-holes are ideally the only connection between the two emitter layers. The first device allows measuring the resistance of a single via hole. The second device features a plurality of via holes, in order to determine the resistance of 25...100 via-holes in parallel. Subtracting spreading resistance and geometry contributions with an analytical approach the via-hole resistance can be deduced from both methods. The presented approach reveals the series resistance contribution of the emitter via-hole independently of the complete solar cell device. Further it permits to test a variety of emitter formation processes, metallization schemes and damage etching or texturization steps regarding their specific series resistance contribution or the general feasibility of a process sequence respectively.