Non-Equilibrium Doping of Poly-Si:Ga/SiOx Passivating Contacts Solar Cells: Paper No. 020004

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

Research output: Contribution to conferencePaper

Abstract

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 poly- Si/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 (5x10^19 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 1x10^20 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 m..omega.. cm^2 is obtained using Ti/Ag contacts, with minimal metal-to-semiconductor contact resistivity of 0.9 m..omega.. cm^2.
Original languageAmerican English
Number of pages6
DOIs
StatePublished - 2022
EventSiliconPV 2021: The 11th International Conference on Crystalline Silicon Photovoltaics - Hamelin, Germany
Duration: 19 Apr 202123 Apr 2021

Conference

ConferenceSiliconPV 2021: The 11th International Conference on Crystalline Silicon Photovoltaics
CityHamelin, Germany
Period19/04/2123/04/21

NREL Publication Number

  • NREL/JA-5900-79755

Keywords

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

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