Non-Equilibrium Doping of Poly-Si:Ga/SiOx Passivating Contacts Solar Cells

Kejun Chen, Enrico Napolitani, San Theingi, Harvey Guthrey, William Nemeth, Matthew Page, Paul Stradins, Sumit Agarwal, David Young

Research output: Contribution to conferencePaperpeer-review


In this contribution, we show that Ga-hyperdoped poly-Si/SiOx contacts are realized by pulsed laser annealing and post-hydrogenation. The motivation behind this work is to improve the inferior performance of boron-doped polySi/SiOx contacts when compared to the phosphorus-doped contacts. Here we used Ga as a novel p-type dopant to replace B, as B is known to accumulate at the interface between the oxide and the crystalline silicon and cause recombination. Due to a high diffusivity of Ga in oxide and a much higher segregation coefficient (Si:SiOx), Ga is shown to be immune to the oxide pileup phenomenon. However, Ga has a low solid solubility limit in Si (5×1019 cm-3), which is not enough to form a low resistivity contact. To overcome this problem, we explored pulsed laser annealing via excimer laser by varying the laser energy densities and pulses. The passivation and electrical properties are studied systematically using photoluminescence (PL), secondary ion mass spectrometry (SIMS), and Van der Pauw-Hall measurements. We show an active Ga doping concentration above 1×1020 cm-3, which is above the solid solubility limit of Ga in Si. Good passivation quality is demonstrated with the highest implied Voc (iVoc) of 721 mV on single side polished samples. Furthermore, a low diode contact resistivity of ~22 mȍÂ cm2 is obtained using Ti/Ag contacts, with minimal metal-to-semiconductor contact resistivity of 0.9

Original languageAmerican English
Number of pages6
StatePublished - 24 Aug 2022
Event11th International Conference on Crystalline Silicon Photovoltaics, SiliconPV 2021 - Hamelin, Virtual, Germany
Duration: 19 Apr 202123 Apr 2021


Conference11th International Conference on Crystalline Silicon Photovoltaics, SiliconPV 2021
CityHamelin, Virtual

Bibliographical note

Publisher Copyright:
© 2022 American Institute of Physics Inc.. All rights reserved.

NREL Publication Number

  • NREL/JA-5900-79755


  • non-equilibrium doping
  • passivating contact
  • photovoltaic
  • poly Si/SiOx
  • solar cell


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