Analysis of Depletion-Region Collection in GaInNAs Solar Cells

Research output: Contribution to conferencePaper


We provide qualitative insight into depletion-region collection in GaInNAs cells to (1) understand the effect of diffusion length L on the QE; and (2) describe the magnitude of L required to get adequate current from the cell. We use Wolf's equations for the QE including a drift field E, and model E as being equal to the junction built-in voltage distributed uniformly across the depletion region.This allows us to calculate the QE as a function of L and depletion width WD. We show that if L is sufficiently small, increasing WD can actually decrease the QE. To determine how long L needs to be in a practical GaInNAs junction, we calculate from the QE the short-circuit current density as a function of WD and L. This allows us to estimate that Lambipolar needs to be greater than roughly 1 ?min order to obtain enough photocurrent for the 4-junction application, giving guidance to the experimental effort to develop such cells.
Original languageAmerican English
Number of pages7
StatePublished - 2005
Event31st IEEE Photovoltaics Specialists Conference and Exhibition - Lake Buena Vista, Florida
Duration: 3 Jan 20057 Jan 2005


Conference31st IEEE Photovoltaics Specialists Conference and Exhibition
CityLake Buena Vista, Florida

NREL Publication Number

  • NREL/CP-520-37418


  • depletion-region collection
  • drift field
  • photocurrent
  • PV
  • quantum efficiency (QE)
  • solar cells


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