Sources of Fluxes of Energy, Heat, and Diffusion Heat in a Bipolar Semiconductor: Influence of Nonequilibrium Charge Carriers

Journal of Applied Physics

Aleksić

et al. 2022

The reduction of the photogenerated charge carriers' influence in periodically illuminated thin silicon membranes is investigated by using the experimental setup of an open photoacoustic cell in the standard range of modulation frequencies from 20 Hz to 20 kHz. It is confirmed that the deposition of a 200 nm thin film of titanium dioxide on the 30- and 50 μm silicon membrane leads to a large increase of the thermoelastic component of the photoacoustic signal, which restores the flexibility lost to the membrane under the influence of photogenerated carriers. The effect of the thermoelastic component enhancement is analyzed by observing the displacement of the tested samples along the heat propagation axis, depending on the carrier density and temperature differences on the illuminated and unilluminated sides, for different membrane thicknesses and a constant film thickness. It is found that the effect of enhancement of several orders of magnitude is more visible in thinner membranes due to higher ratios between the film and membrane thicknesses.

Section: Introductionmentioning

confidence: 99%

Enhancement of the thermoelastic component of the photoacoustic signal of silicon membranes coated with a thin TiO2 film

Journal of Applied Physics

Aleksić

et al. 2022

“…[4][5][6] Photogenerated excess carriers can change the heat transport dynamics and temperature profiles inside semiconductors. [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.…”

Section: Introductionmentioning

confidence: 99%

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

Journal of Applied Physics

Aleksić

Pantić

et al. 2020

Based on the experimental and theoretical signals of an open photoacoustic cell operating with modulation frequencies from 20 Hz to 20 kHz, a significant contribution of photogenerated excess carriers on the thermal and thermoelastic responses of an n-type silicon plate is observed for the very first time. This is achieved by comparing the measured amplitude and phase of the photoacoustic signal with their corresponding theoretical thermoelastic counterparts, for high enough modulation frequencies mainly. It is shown that the amplitude of the thermoelastic component of plasma-thin samples varies about two orders of magnitude with respect to the corresponding one of plasma-thick samples. Furthermore, we find a maximal temperature difference ΔT = − 35 nK between the illuminated and non-illuminated sample surfaces, which shows that thin silicon plates with excess carriers could be used as heat sinks.

“…Slow thermal sources exist due to the recombination of carriers in the bulk and on the surface of the sample. Slows are directly dependent on the density of the photogenerated carriers [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

The surface recombination velocity and bulk lifetime influences on photogenerated excess carrier density and temperature distributions in n-type silicon

Facta Univ Electron Energ

Galović

et al. 2018

The temperature distributions in the n-type silicon circular plate, excited by a frequency-modulated light source from one side, are investigated theoretically in the frequency domain. The influence of the photogenerated excess carrier density on the temperature distributions is considered with respect to the sample thickness, surface quality and carrier lifetime. The presence of the thermalization and non-radiative recombination processes are taken into account. The existence of the fast and slow heat sources in the sample is recognized. It is shown that the temperature distribution on sample surfaces is a sensitive function of an excess carrier density under a bulk and surface recombination. The most favorable values of surface velocities ratio and bulk lifetime are established, assigned for a simpler and more effective analysis of the carrier influence in semiconductors. The photothermal and photoacoustic transmission detection configuration is proposed as a most suitable experimental scheme for the investigation of the excess carrier influence on the silicon surface temperatures. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON171016]