Relative sensitivity of photomodulated reflectance and photothermal infrared radiometry to thermal and carrier plasma waves in semiconductors

Abstract

Articles you may be interested inSemiconductor microwave mirror for a measurement of the dynamical Casimir effect Rev. Sci. Instrum. 75, 4967 (2004); 10.1063/1.1808892Carrier-density-wave transport property depth profilometry using spectroscopic photothermal radiometry of silicon wafers I: Theoretical aspects J. Appl. Phys. 93, 5236 (2003); 10.1063/1.1565498Carrier-density-wave transport property depth profilometry using spectroscopic photothermal radiometry of silicon wafers II: Experimental and computational aspects A quantitative theoretical comparison between two photothermal techniques-the photomodulated reflectance ͑PMR͒ and the photothermal infrared radiometry ͑PTR͒-from the standpoint of their relative sensitivity to the thermal and carrier plasma waves in semiconductors is presented. The coefficients representing the relative contributions from the thermal and plasma waves to the total PMR and PTR signals arising as a result of the same temperature increase and photoinjected excess carrier concentration are calculated for three crystalline semiconductors: Si, Ge, and GaAs. The PTR signal is found to be extremely sensitive to the plasma-wave effects exhibiting up to five orders of magnitude higher carrier plasma-to-thermal contrast than that of the PMR method.

Minority carrier recombination lifetimes in n-type CdMgSe mixed crystals measured by means of the photothermal infrared radiometry

“…(1). It turns that the thermal component C t is proportional to the infrared absorption coe− fficient [11]. In the frame of the classical Drude theory the infrared absorption coefficient is proportional to the carrier concentration N. Hence, the thermal−to−plasma component coefficient A is proportional to the carrier concentration N. The observed linear relation between the carrier concentra− tion and the thermal−to−plasma component coefficient, as well as the estimated value of hole diffusion length in CdSe indicate that it is possible to estimate the carrier recombina− tion lifetime as short as 0.1 μs by PTR method at fre− quencies below the characteristic knee.…”

“…It causes a modulation of the constant IR radiation of the sample being the result of a free carrier absorption of this radiation. In general the photothermal infrared radio− metry frequency signal is a sum of thermal and plasma components [11] …”

“…The thermal and plasma waves are the result of the illumination of the sample by the intensity mod− ulated beam of light. The theory and experiment of the PTR method was described in papers [10][11][12][13][14][15][16][17][18][19][20]. The PTR method was used to obtain information about carrier transport parameters such as carrier recombination lifetimes, surface recombination velocities and carrier diffusion coefficients.…”

Determination of the carrier concentration in CdSe crystals from the effective infrared absorption coefficient measured by means of the photothermal infrared radiometry

“…Photothermal radiometry (PTR) is a non-contact method which enables to measure optical and thermal parameters of materials [1,2]. In the case of semiconductors, PTR additionally yields information about the recombination parameters [3,4]. Recently, it was found that for infrared (IR) semitransparent semiconductors, it is possible to obtain information on the carrier concentration with quantitative values after calibration to Hall carrier concentration [5].…”

Photo-carrier radiometry of semiconductors: A novel powerful optoelectronic diffusion-wave technique for silicon process non-destructive evaluation

“…Reviews of the subject matter have been presented by Mandelis [1] and Christofides et al [2]. The major advantage of PTR over other photothermal techniques, such as photomodulated thermoreflectance (PMOR), has been found to be the higher sensitivity of PTR to the photo-excited free carrier-density-wave (the modulated-laser driven oscillating electronic diffusionwave [3]) than PMOR [4,5]. This advantage exists due to domination of the free-carrier wave over the superposed thermal-wave (TW) contributions to the PTR signal.…”