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

Abstract

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]

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

“…0), while the non-illuminated one remains active (s 2 ) 0). 22 In this latter case, the PA response of plasma-thin semiconductors (l/L p , 1) was found to be completely different than that of plasma-thick ones (l/L p . 1).…”

“…[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.…”

“…In our recent theoretical studies of n-type silicon circular plates, 22,23 we noticed that the impact of photogenerated excess carriers on their PA response depends mostly on the semiconductor surface quality determined by the surface recombination speed s, the sample thickness l, and the carrier diffusion length L p ¼ ffiffiffiffiffiffiffi ffi D p τ p , with D p being the diffusion coefficient of the minority carriers with lifetime τ. Favorable conditions for the observation of this impact were found when the illuminated sample surface is passivated (s 1 !…”

“…23 In other words, the excess carriers of plasmathin samples can be used to remove the absorbed light energy from the illuminated surface and transfer it to the non-illuminated one, and, therefore, these materials could become efficient heat sinks. On the other hand, taking into account that the amplitude of the thermoelastic (TE) component of the PA signal of plasma-thin samples is significantly attenuated at low modulation frequencies (f < 1 kHz) and exhibits a typical peak-like shape at high ones (f > 1 kHz), 22,23 the bending of these materials can show up at high modulation frequencies, mainly.…”

Development and Comparison of the Techniques for Solving the Inverse Problem in Photoacoustics

“…Photoacoustics is a non-destructive experimental technique, being extensively developed over the last forty years and finding its application in the characterization and imaging of various materials and devices (Bialkowski 1996;Tam 1986;Vargas and Miranda 1988) The oldest and the most widespread PA technique is frequency gas-microphone method (Galovic et al 2014;Rosencwaig and Gerscho 1976;Rousset et al 1983), which has proven to be very efficient in determination of optical, thermal and elastic properties of semiconductors, semiconductor structures, metals, composite materials, ceramics, polymers, etc. (Balderas-Lopez and Mandelis 2001;Mansanares et al 1991;Markushev et al 2018;Nesic et al 2018;Todorović and Nikolic 2000). In frequency photoacoustics, the sample is illuminated by a monochromatic EM beam of harmonically modulated intensity.…”