Terahertz photoconductance dynamics of semiconductors from sub-nanosecond to millisecond timescales

Optical pump terahertz probe spectroscopy (OPTP) is a versatile non-contact technique that measures transient photoconductance decays with femtosecond temporal resolution. However, its maximum temporal range is limited to only a few nanoseconds by the mechanical delay lines used. We extended the tem...

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Bibliographic Details
Published in:Applied physics letters 2023-01, Vol.122 (1)
Main Authors: Butler-Caddle, Edward, Grant, Nicholas E., Pain, Sophie L., Murphy, John D., Jayawardena, K. D. G. Imalka, Lloyd-Hughes, James
Format: Article
Language:English
Subjects:
Applied physics
Decay
Delay lines
Electric contacts
Germanium
Metal halides
Perovskites
Silicon
Temporal resolution
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Summary:Optical pump terahertz probe spectroscopy (OPTP) is a versatile non-contact technique that measures transient photoconductance decays with femtosecond temporal resolution. However, its maximum temporal range is limited to only a few nanoseconds by the mechanical delay lines used. We extended the temporal range of OPTP to milliseconds and longer while retaining sub-nanosecond resolution. A separate pump laser was electrically synchronized to the probe pulses, allowing the pump–probe delay to be controlled with an electronic delay generator. We demonstrated the capabilities of this technique by examining the photoconductance decays of semiconductors with lifetimes ranging over six orders of magnitude: III-Vs, metal halide perovskites, germanium, and silicon. A direct comparison of results on silicon from OPTP and inductively coupled photoconductance decay highlighted the higher spatial and temporal resolution of OPTP, which allowed in-plane and out-of-plane carrier diffusion to be studied.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0130721