On the Photoacoustic Characterization of Semiconductors: Influence of Carrier Recombination on the Thermodiffusion, Thermoelastic and Electronic Strain Signal Generation Mechanisms

Abstract

A quantitative study of the photoacoustic (PA) signal dependence on the modulation frequency in semiconductors was performed. The carrier recombination processes were taken into account to calculate the PA signal, considering the thermodiffusion (TD), thermoelastic (TE) and electronic strain (ES) signal generation mechanisms. Analytical expressions for these contributions and for the total pressure in the PA gas chamber are given for the heat transmission detection configuration. The theoretical results were compared with measurements in Si samples, showing a good agreement. An anomalous behavior of the PA signal dependence on the modulation frequency can only be explained, if the ES contribution is added to the other ones.

Photoacoustic investigations on thermal diffusivity of CuGa1–xFexO2

“…The experimental set-up is standardized using a silicon wafer of thickness 420 µm and indium phosphide of thickness 350 µm. We obtained thermal diffusivity values of 0.93 ± 0.007 cm 2 s −1 for silicon wafer and 0.42 ± 0.002 cm 2 s −1 for indium phosphide, which are in accordance with the literature values [22,23]. The samples, in the form of discs of diameter 1 cm are fixed on to the cell using vacuum grease.…”

Experimental photoacoustic observation of the photogenerated excess carrier influence on the thermoelastic response of n-type silicon

“…[7][8][9][10][11][12][13] In photoacoustics (PA), for instance, some theoretical studies showed that the number of photogenerated excess carriers generated in both n-and p-type semiconductors illuminated with a modulated light source increases with the light absorption, and they are able to significantly change the temperature distribution at the surface and inside the materials. [14][15][16][17][18] The experimental observation of these effects still remains a challenge due to the separate analysis of either the amplitude or phase of the PA signal in a relatively short range of modulation frequencies. [19][20][21][22][23] The simultaneous monitoring of both of these signals in a wide interval of modulation frequencies is thus desirable to observe the effects of photogenerated excess carriers.…”