Effect of Na Incorporation on the Growth and Properties of CdTe/CdS Devices

Research output: Contribution to conferencePaper

Abstract

Sodium is known to enhance p-type doping in copper indium diselenide (CIS)-based devices fabricated on soda-lime glass substrates, and similar amounts of Na are present in commercial cadmium telluride (CdTe) devices. We present the results on the effects of Na incorporation on the properties of CdTe/CdS solar cells prepared on borosilicate glass substrates. A NaF layer 10 to 30 nm thick wasincorporated at either the CdS/CdTe interface or on the CdTe surface, as a source of Na. CdTe layers were deposited by close-spaced sublimation at substrate temperatures from 425?C (LT) to 620?C (HT), followed by heat-treatment in the presence of CdCl2 vapor. Atomic force microscopy analysis showed that the samples with NaF at the CdS/CdTe interface deposited in He ambient have larger grainswith a sub-grain structure that disappears after CdCl2 heat treatment accompanied by an increase in grain size. Samples deposited in O2 ambient have smaller grains without a sub-grain structure. For samples with NaF deposited on the CdTe surface, LT samples with CdCl2 heat treatment showed a morphology similar to samples without NaF layers; but samples heat-treated in He ambient at 500?C priorto CdCl2 treatment showed a different microstructure with platelets on the surface.
Original languageAmerican English
Number of pages8
StatePublished - 2005
Event31st IEEE Photovoltaics Specialists Conference and Exhibition - Lake Buena Vista, Florida
Duration: 3 Jan 20057 Jan 2005

Conference

Conference31st IEEE Photovoltaics Specialists Conference and Exhibition
CityLake Buena Vista, Florida
Period3/01/057/01/05

NREL Publication Number

  • NREL/CP-520-37368

Keywords

  • atomic force microscopy (AFM)
  • cadmium telluride (CdTe) photovoltaic solar cells modules
  • copper indium diselenide (CIS)
  • devices
  • p-Type doping
  • PV
  • soda lime glass (SLG)
  • substrates

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