Photoacoustic investigation of doped InP using open cell configuration

Abstract

An open cell photoacoustic (PA) configuration has been employed to evaluate the thermal diffusivity of intrinsic InP as well as InP doped with tin and iron. Thermal diffusivity data have been evaluated from variation of phase of PA signal as a function of modulation frequency. In doped samples, we observe a reduced value for thermal diffusivity in comparison with intrinsic InP. We also observed that, while the phase of the PA signal varies linearly with the square root of chopping frequency for doped samples, the intrinsic material does not exhibit such behaviour in the experimental frequency range. These results have been interpreted in terms of the heat generation and phonon assisted heat diffusion mechanisms in semiconductors.

Photothermal deflection studies on heat transport in intrinsic and extrinsic InP

“…Addition of controlled amounts of deep level impurities create midgap energy levels, which can act as recombination centers when there are excess carriers in the semiconductors and as generation centers when the carrier concentration is below its equilibrium value as in the reverse biased space region of pn junction or MOS capacitors [27]. Thus Fe doping results in midgap energy levels, which are known to create a large lattice relaxation around them, thereby acting as effective scattering centers for phonons [28]. As noted above, this increase in scattering centers reduces phonon mean free path and gives a reduced value for thermal diffusivity in Fe doped semi insulating InP.…”

Photoacoustic study of the effect of doping concentration on the transport properties of GaAs epitaxial layers

“…Some of the recent investigations show that doping can definitely influence the thermal diffusivity and surface recombination velocity of compound semiconductors. [9][10][11][12] In this paper, we present the results of our PA measurements on an epitaxial layer of GaAs doped with different concentration of Si, grown on a GaAs substrate by molecular beam epitaxy ͑MBE͒. Amplitude of the PA signal gives a clear picture of the various heat generation mechanisms in semiconductors.…”

“…[1][2][3][4][5][6][7][8][9][10] All the photothermal methods are based on the detection, by one means or other, of thermal waves generated in the sample after excitation with modulated optical radiation. In the simple and elegant PA technique these thermal waves produce density fluctuations in the specimen and the surrounding medium, which can be detected either by a sensitive microphone or by a piezoelectric transducer.…”