Minority and Majority Charge Carrier Mobility in Cu2ZnSnSe4 Revealed by Terahertz Spectroscopy

Ingrid Repins, Hannes Hempel, Charles Hadges, Rainer Eichberger, Thomas Unold

Research output: Contribution to journalArticlepeer-review

27 Scopus Citations


The mobilities of electrons and holes determine the applicability of any semiconductor, but their individual measurement remains a major challenge. Here, we show that time-resolved terahertz spectroscopy (TRTS) can distinguish the mobilities of minority and majority charge carriers independently of the doping-type and without electrical contacts. To this end, we combine the well-established determination of the sum of electron and hole mobilities from photo-induced THz absorption spectra with mobility-dependent ambipolar modeling of TRTS transients. The method is demonstrated on a polycrystalline Cu2ZnSnSe4 thin film and reveals a minority (electron) mobility of 128 cm2/V-s and a majority (hole) carrier mobility of 7 cm2/V-s in the vertical transport direction relevant for light emitting, photovoltaic and solar water splitting devices. Additionally, the TRTS analysis yields an effective bulk carrier lifetime of 4.4 ns, a surface recombination velocity of 6 * 104 cm/s and a doping concentration of ca. 1016 cm−3, thus offering the potential for contactless screen novel optoelectronic materials.

Original languageAmerican English
Article numberArticle No. 14476
Number of pages9
JournalScientific Reports
Issue number1
StatePublished - 1 Dec 2018

Bibliographical note

Publisher Copyright:
© 2018, The Author(s).

NREL Publication Number

  • NREL/JA-5K00-72460


  • CZTS
  • kesterite
  • mobility
  • spectroscopy
  • terahertz


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