Thermoelectric properties of electrodeposited tellurium films and the sodium lignosulfonate effect

Mayor, Begoña Abad; Rull-Bravo, Marta; Hodson, Stephen L.; Xu, Xianfan; Martín‐González, Marisol

doi:10.1016/j.electacta.2015.04.063

Cited by 52 publications

(39 citation statements)

References 41 publications

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“…The increment of phonon scattering can therefore be reduced by introduction of pores as lattice imperfections Theoretical studies show a significant reduction in thermal conductivity for generating such microsegregations local inhomogeneity that has an important role in reducing κ [28]. Table 1 shows the thermal conductivities of films treated at 500°C, which were measured using the photoacoustic technique [29].Thermalconductivitiesof1.13 W•m −1 •K −1 and 1.23 W•m −1 •K −1 were found for in situ and ex situ thermal-treated films, respectively. Scanning thermal microscopy (SThM) measurements of these samples were also performed with reproducibility and they agree within the uncertainty associated with the experimental error [30].…”

Section: Thermoelectric Characterizationmentioning

confidence: 99%

Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering

Taborda¹,

Romero²,

Mayor³

et al. 2016

Nanotechnology

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Si x Ge1-x alloys are well-known thermoelectric materials with a high figure of merit at high temperatures. In this work, metal-induced crystallization (MIC) has been used to grow Si0.8Ge0.2 films that present improved thermoelectric performance (zT = 5.6 × 10(-4) at room temperature)--according to previously reported values on films--with a relatively large power factor (σ · S (2) = 16 μW · m(-1) · K(-2)). More importantly, a reduction in the thermal conductivity at room temperature (κ = 1.13 ± 0.12 W · m(-1) · K(-1)) compared to other Si-Ge films (∼3 W · m(-1) · K(-1)) has been found. Whereas the usual crystallization of amorphous SiGe (a-SiGe) is achieved at high temperatures and for long times, which triggers dopant loss, MIC reduces the crystallization temperature and the heating time. The associated dopant loss is thus avoided, resulting in a nanostructuration of the film. Using this method, we obtained Si0.8Ge0.2 films (grown by DC plasma sputtering) with appropriate compositional and structural properties. Different thermal treatments were tested in situ (by heating the sample inside the deposition chamber) and ex situ (annealed in an external furnace with controlled conditions). From the studies of the films by: x-ray diffraction (XRD), synchrotron radiation grazing incidence x-ray diffraction (SR-GIXRD), micro Raman, scanning electron microscopy (SEM), x-ray photoemission spectroscopy (XPS), Hall effect, Seebeck coefficient, electrical and thermal conductivity measurements, we observed that the in situ films at 500 °C presented the best zT values with no gold contamination.

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Section: Thermoelectric Characterizationmentioning

confidence: 99%

Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering

Taborda¹,

Romero²,

Mayor³

et al. 2016

Nanotechnology

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“…To explore the validity of this assumption, ℎ vs. was plotted for each sample. To this end, a sample with known Seebeck coefficient and thermal conductivity (Sb-doped ptype Bi2Te3, with κ=1.0 W/K·m and S=172 ± 11 µV/K, as measured by the Seebeck Microprobe technique 26 ) was scanned and the absolute value of the Seebeck voltage was measured at different locations, and averaged. Note that the curves intersect at = 2.8 ± 0.…”

Section: Figure 3a)(left)exemplary Graph Of Measured Average Probe Thmentioning

confidence: 99%

Thermal conductivity measurements of high and low thermal conductivity films using a scanning hot probe method in the 3ω mode and novel calibration strategies

et al. 2015

Self Cite

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This work discusses measurement of thermal conductivity (k) of films using a scanning hot probe method in the 3ω mode and investigates the calibration of thermal contact parameters, specifically the thermal contact resistance (R(th)C) and thermal exchange radius (b) using reference samples with different thermal conductivities. R(th)C and b were found to have constant values (with b = 2.8 ± 0.3 μm and R(th)C = 44,927 ± 7820 K W(-1)) for samples with thermal conductivity values ranging from 0.36 W K(-1) m(-1) to 1.1 W K(-1) m(-1). An independent strategy for the calibration of contact parameters was developed and validated for samples in this range of thermal conductivity, using a reference sample with a previously measured Seebeck coefficient and thermal conductivity. The results were found to agree with the calibration performed using multiple samples of known thermal conductivity between 0.36 and 1.1 W K(-1) m(-1). However, for samples in the range between 16.2 W K(-1) m(-1) and 53.7 W K(-1) m(-1), calibration experiments showed the contact parameters to have considerably different values: R(th)C = 40,191 ± 1532 K W(-1) and b = 428 ± 24 nm. Finally, this work demonstrates that using these calibration procedures, measurements of both highly conductive and thermally insulating films on substrates can be performed, as the measured values obtained were within 1-20% (for low k) and 5-31% (for high k) of independent measurements and/or literature reports. Thermal conductivity results are presented for a SiGe film on a glass substrate, Te film on a glass substrate, polymer films (doped with Fe nano-particles and undoped) on a glass substrate, and Au film on a Si substrate.

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“…With further investigation on the composition of the strands using EDX as shown in Figure 2 (e-f), it was observed that the strands show an atomic composition of 75.6% for Te and 24.4% for Cd. The presence of the Te-rich strands has also been documented in the literature [19], [20] and as it is well known that an introduction of an acidic media to CdTe attacks Cd leaving rich Te surface [15], [21]. This observation signifies the detrimental effect of pH1 CdCl 2 for post-growth-treatment on the material quality of the glass/FTO/n-CdS/n-CdTe all-electrodeposited layers and may result in the reduction in the device quality.…”

Section: Optical Property Analysismentioning

confidence: 63%

Optimisation of pH of cadmium chloride post-growth-treatment in processing CDS/CDTE based thin film solar cells

Ojo

Dharmadasa

2017

J Mater Sci: Mater Electron

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The role of Chlorine-based activation in the production of high quality CdS/CdTe photovoltaic have been well discussed and explored with an overlook of the effect of Cadmium chloride (CdCl 2) post-growth treatment acidity on the property of the fabricated devices. This work focuses on the optimisation of CdCl 2 post-growth treatment pH as it affects both the material and fabricated device properties of all-electrodeposited multilayer glass/FTO/n-CdS/n-CdTe/p-CdTe configuration. CdCl 2 treatments with acidity ranging from pH1 to pH4 were explored. The properties of the ensued CdTe layer were explored using optical, morphological, compositional structural and electrical property analysis, while, the effect on fabricated multilayer glass/FTO/n-CdS/n-CdTe/p-CdTe configuration were also explored using both I-V and C-V measurements. Highest improvements in the optical, morphological, compositional and structural were observed at pH2 CdCl 2 post-growth treatment with an improvement in absorption edge, grain size, crystallinity and crystallite size. Conductivity type conversions from n-CdTe to p-CdTe, increase in pin-hole density and collapse of the absorption edge were observed after pH1 CdCl 2 treatment. The highest fabricated solar cell efficiency of 13% was achieved using pH2 CdCl 2 treatment as compared to other pH values explored.

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Thermoelectric properties of electrodeposited tellurium films and the sodium lignosulfonate effect

Cited by 52 publications

References 41 publications

Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering

Low thermal conductivity and improved thermoelectric performance of nanocrystalline silicon germanium films by sputtering

Thermal conductivity measurements of high and low thermal conductivity films using a scanning hot probe method in the 3ω mode and novel calibration strategies

Optimisation of pH of cadmium chloride post-growth-treatment in processing CDS/CDTE based thin film solar cells

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