Photoacoustic characterization of semiconductors: Transport properties and thermal diffusivity in GaAs and Si

Abstract

The photoacoustic signal of two semiconductor samples is investigated as a function of the modulation frequency in a heat-transmission configuration.It is shown that, in the frequency range where the sample is thermally thick, the signal amplitude and phase can single out the different fast and slow nonradiative recombination heat sources responsible for the photoacoustic signal. The characterization of the thermal and the carrier transport properties is discussed and some practical procedures for this purpose are also outlined.

Preparation and Thermal Characterization of Annealed Gold Coated Porous Silicon

“…Before characterising the PSi samples, the optical setup and measuring procedures were tested with a c-Si wafer and the TD values for the four samples were found between 0.84–0.90 cm 2 /s, in good agreement with values in the literature [24,25,26,27]. This measurement was done for silicon and Au/PSi before and after annealing, and also PSi before annealing, in order to measure and trace the variation of TD in the different conditions of this study.…”

Photoacoustic investigation of doped InP using open cell configuration

“…[5], the heat generation phenomenon in semiconductors after irradiation with chopped optical beam arises due to three processes namely thermalisation, nonradiative S.D. GEORGE et al 76…”

“…The TDC, which is basis of design of the Open Photoacoustic Cell (OPC), is extensively used to measure both thermal and transport properties of a large number of samples such as GaAs, Si, Solar cells, CdInGeS 4 , PbTe, etc. [4,5,8]. However, the effect of doping on the thermal and transport properties of semiconductor samples has not been studied in detail, except for a few reports [9,10].…”

“…The transport properties and lifetimes of the photoexcited carriers have also been studied using PA technique. A detailed discussion of the contributions of various factors to thermal flux in semiconductors under periodic optical excitation is given by Pinto Neto et al [4,5]. In their work they studied the influence of carrier recombination and diffusion in PbTe and Si as well as thermal diffusivity of GaAs and Si.…”

“…The thermal diffusivity values of various semiconductors have been evaluated in the past by measuring PA signal as a function of modulation frequency [4,5]. The transport properties and lifetimes of the photoexcited carriers have also been studied using PA technique.…”