Excitation-Dependent Carrier lifetime and Diffusion Length in Bulk CdTe Determined by Time-Resolved Optical Pump-Probe Techniques

Darius Kuciauskas, Patrik Scajev, Saulius Miasojedovas, Algirdas Mekys, Kelvin Lynn, Santosh Swain, Kestutis Jarasiunas

Research output: Contribution to journalArticlepeer-review

39 Scopus Citations

Abstract

We applied time-resolved pump-probe spectroscopy based on free carrier absorption and light diffraction on a transient grating for direct measurements of the carrier lifetime and diffusion coefficient D in high-resistivity single crystal CdTe (codoped with In and Er). The bulk carrier lifetime τ decreased from 670 ± 50 ns to 60 ± 10 ns with increase of excess carrier density N from 1016 to 5 × 1018 cm-3 due to the excitation-dependent radiative recombination rate. In this N range, the carrier diffusion length dropped from 14 μm to 6 μm due to lifetime decrease. Modeling of in-depth (axial) and in-plane (lateral) carrier diffusion provided the value of surface recombination velocity S = 6 × 105 cm/s for the untreated surface. At even higher excitations, in the 1019-3 × 1020 cm-3 density range, D increase from 5 to 20 cm2/s due to carrier degeneracy was observed.

Original languageAmerican English
Article numberArticle No. 025704
Number of pages9
JournalJournal of Applied Physics
Volume123
Issue number2
DOIs
StatePublished - 14 Jan 2018

Bibliographical note

Publisher Copyright:
© 2018 Author(s).

NREL Publication Number

  • NREL/JA-5900-70419

Keywords

  • electrical properties
  • light defraction
  • optical properties
  • pump probe experiments
  • semiconductors

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