Carrier Concentration Dependence of Photoacoustic Signal Intensity of Silicon

Abstract

Photoacoustic (PA) spectra near the energy gap of n- and p-type silicon were investigated at various carrier concentrations. The PA signal intensity at energies lower than the energy gap increased with increasing carrier concentration for both types. The increase is considered to be due to the increase in the heat generated in the samples following free carrier absorption and nonradiative relaxation processes. The PA signal intensity increased drastically above a carrier concentration of 1017 cm-3 for n-type and above that of 1016 cm-3 for p-type silicon.

Photoacoustic studies on <bold>n</bold>-type InP

“…19 Note also that in many OPC studies involving a variety of semiconductors, more complex phase behavior with a minimum in the phase plot is reported. [9][10][11][12][13][14][15][16][17] This nonlinear behavior of the phase data is attributed to surface and bulk recombination processes of photogenerated carriers in those materials. However, our observation indicates that for this sample, the photogenerated excess carrier recombination processes do not contribute to the PA signal in any significant manner in the frequency range of our investigations.…”

“…The Dramicanin model is very useful for the analysis of PA signal amplitude and phase at the front and rear surfaces of semiconductor samples. Subsequently, in more recent years, using PA phase measurements in the heat transmission configuration, carrier transport properties such as carrier diffusion coefficient, carrier recombination velocity, and mean recombination time were evaluated together with the thermal diffusivity of a large number of semiconducting samples, [9][10][11][12][13][14][15][16][17] namely, GaAs, CdTe, Si solar cells, CdInGaS 4 , InSb, GaSb, etc.…”