Spectrally resolved modulated infrared radiometry of photothermal, photocarrier, and photoluminescence response of CdSe crystals: Determination of optical, thermal, and electronic transport parameters
- Multiscale Thermophysics Lab. GRESPI, Université de Reims Champagne Ardenne URCA, Moulin de la Housse BP 1039, 51687 Reims (France)
- Institut für Experimentalphysik VI, Ruhr-Universität Bochum, 44801 Bochum (Germany)
Spectrally resolved modulated infrared radiometry (SR-MIRR) with super-band gap photoexcitation is introduced as a self-consistent method for semiconductor characterization (CdSe crystals grown under different conditions). Starting from a theoretical model combining the contributions of the photothermal (PT) and photocarrier (PC) signal components, an expression is derived for the thermal-to-plasma wave transition frequency f{sub tc} which is found to be wavelength-independent. The deviation of the PC component from the model at high frequency is quantitatively explained by a quasi-continuous distribution of carrier recombination lifetimes. The integral, broad frequency band (0.1 Hz–1 MHz) MIRR measurements simultaneously yielded the thermal diffusivity a, the effective IR optical absorption coefficient β{sub eff}, and the bulk carrier lifetime τ{sub c}. Spectrally resolved frequency scans were conducted with interchangeable IR bandpass filters (2.2–11.3 μm) in front of the detector. The perfect spectral match of the PT and PC components is the direct experimental evidence of the key assumption in MIRR that de-exciting carriers are equivalent to blackbody (Planck) radiators. The exploitation of the β spectrum measured by MIRR allowed determining the background (equilibrium) free carrier concentration n{sub 0}. At the shortest wavelength (3.3 μm), the photoluminescence (PL) component supersedes the PC one and has distinct features. The average sample temperature influences the PC component but not the PT one.
- OSTI ID:
- 22594527
- Journal Information:
- Journal of Applied Physics, Vol. 119, Issue 12; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
BETA SPECTRA
CADMIUM SELENIDES
CARRIER LIFETIME
CARRIERS
CONCENTRATION RATIO
CRYSTALS
INFRARED SPECTRA
PHOTOLUMINESCENCE
PLASMA WAVES
SEMICONDUCTOR MATERIALS
SIGNALS
THERMAL DIFFUSIVITY
TRANSPORT THEORY
WAVELENGTHS