Electrical Analysis of Pulsed Laser Annealed Poly-Si: Ga/SiOx Passivating Contacts: Paper No. 020002

Kejun Chen, Enrico Napolitani, Chun-Sheng Jiang, Matteo De Tullio, Francesco Sgarbossa, San Theingi, William Nemeth, Matthew Page, Sumit Agarwal, Paul Stradins, David Young

Research output: Contribution to conferencePaper

Abstract

In this contribution, we examine Ga hyper-doped poly-Si/SiOx contacts realized by pulsed laser melting (PLM). Here, we use Ga as a novel p-type dopant and B as a conventional dopant to induce non-equilibrium doping using an excimer laser. We perform simulations to visualize the maximum melt depth profiles within the poly-Si, with a goal of distributing dopants close to the tunneling oxide, but at the same time preserving the passivation. Hall measurements show that sheet resistance for B is lower than Ga due to its higher solid solubility limit in Si. After comparing the Hall active dopant concentration with the chemical concentration obtained by SIMS measurement, we show nearly 100% activation B activation reaching 10^21 cm-3, while only ~20% activation for Ga. Nevertheless, we achieve active doping concentrations of Ga in poly-Si six times higher than its solid solubility limit in Si (~10^19 cm-3). We compare our Hall mobilities with values in the literature for c-Si and show that B mobilities in laser-treated poly-Si are close to that of the literature value for B, while Ga mobilities are lower, possibly due to additional scattering channels within grain boundaries and deformed lattice. We also compare our results on PLM samples with conventional furnace annealed samples, and we show much higher percent activation and mobilities. Previously, we showed a low contact resistivity of 35.5 +/- 2.4 m..omega..cm2. Here, we further confirm this result by scanning spreading resistance microscopy and Kelvin force nanoprobe microscopy. We demonstrate that our poly-Si: Ga/nCz contact exhibits large drift and diffusion currents under normal cell operating voltage, which widens the laser processing window for a good metal/poly-Si/c-Si contact.
Original languageAmerican English
Number of pages4
DOIs
StatePublished - 2023
EventSiliconPV 2022, the 12th International Conference on Crystalline Silicon Photovoltaics - Konstanz, Germany
Duration: 28 Mar 202230 Mar 2022

Conference

ConferenceSiliconPV 2022, the 12th International Conference on Crystalline Silicon Photovoltaics
CityKonstanz, Germany
Period28/03/2230/03/22

NREL Publication Number

  • NREL/CP-5K00-87324

Keywords

  • high-efficiency solar cells
  • poly-Si
  • pulsed laser melting

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