| Autor: |
Chirtoc, M., Pawlak, M., Horny, N. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 8/14/2023, Vol. 134 Issue 6, p1-9, 9p |
| Abstrakt: |
The radiation intensity dependence of photothermal (PT) and photocarrier (PC) signals from n-type CdSe single crystals was investigated by modulated infrared radiometry (MIRR) in the mid-IR range (5–11.3 μm) with superbandgap photoexcitation. The influence of dc temperature increase of the sample was avoided by a new step-sine modulation method that combines the advantages of transient and periodical modulation. With increasing laser intensity I, the amplitude of the PC component shows a sub-linear dependence (|SPC| ∝ I0.5), while the PT one has the expected linear dependence (|SPT| ∝ I). As a result, the transition frequency ft between the two components is shifted to higher frequencies, which is explained in the frame of a simple model. The origin of the observed effects is the decrease of the effective photocarrier lifetime τ ∝ I−0.5 over three laser intensity decades. In contrast, previous studies on nonlinear PC response in semiconductors performed in the near-IR range (0.7–1.8 μm) have found supra-linear |SPC| dependence with exponent between 1 and 2. This difference is attributed to the fact that the near-IR radiometric signal features characteristics of a photoluminescence (PL) signal that are different from those of the mid-IR PC signal, as shown in our previous study [J. Appl. Phys. 119, 125108 (2016)] on the same CdSe samples. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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