Multichannel spectroscopic ellipsometry for CdTe Photovoltaics: From real-time monitoring to large-scale mapping

Koirala, Prakash; Chen, Jie; Tan, Xinxuan; Podraza, Nikolas J.; Marsillac, Sylvain; Rockett, Angus; Collins, R. W.

doi:10.1109/pvsc.2013.6744861

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…[7] Consequently, we ascribe the rollover to a potential energy barrier for hole transport from the SWCNT to the TEC 15M. Note that the 100 nm i-SnO 2 layer that is part of the TEC 15M stack can interdiffuse with deposited CdS during the normal high temperature device processing that is used for superstrate devices, [28] while such interdiffusion in not expected in the present case because the CdTe and i-SnO2 layers are physically separated by the SWCNT layer.…”

Section: Resultsmentioning

confidence: 68%

Substrate configuration, bifacial CdTe solar cells grown directly on transparent single wall carbon nanotube back contacts

Khanal

Phillips

Song

et al. 2016

Solar Energy Materials and Solar Cells

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Substrate configuration CdTe/CdS solar cells were fabricated directly on a 25 nm thick single wall carbon nanotube (SWCNT) back contacts using a high temperature, commercial deposition process. No copper was introduced to facilitate the formation of an ohmic back contact at the back of the device. The champion device had an efficiency of 6.5%. The thin SWCNT layer allowed the device to be illuminated through the back contact, and a comparison of the device performance with front and backside illumination revealed several novel features of the SWCNT back contact. Our findings indicate that SWCNT films may be useful as a recombination layer contact for bifacial solar cells, photovoltaic windows, or two-terminal thin-film tandem solar cells.

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Section: Resultsmentioning

confidence: 68%

Substrate configuration, bifacial CdTe solar cells grown directly on transparent single wall carbon nanotube back contacts

Khanal

Phillips

Song

et al. 2016

Solar Energy Materials and Solar Cells

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show abstract

“…Finally, an additional means of characterizing the optical properties of MZO-containing device structures is expected to be informative toward the refinement of the M-SE and TG-SE models. In previous studies of CdTe device structures incorporating SnO 2 :F as the transparent conducting oxide and SnO 2 as the HRT layer, infrared spectroscopic ellipsometry (IR-SE) measurements were performed at different stages of fabrication to gain insights into the interaction between adjoining layers [ 59 , 60 ]. In these studies, the role of CdS deposition in modifying the underlying SnO 2 :F free electron and defect properties and the role of the intervening SnO 2 in suppressing these interactions can be characterized.…”

Section: Resultsmentioning

confidence: 99%

Optical Properties of Magnesium-Zinc Oxide for Thin Film Photovoltaics

et al. 2021

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Motivated by their utility in CdTe-based thin film photovoltaics (PV) devices, an investigation of thin films of the magnesium-zinc oxide (MgxZn1−xO or MZO) alloy system was undertaken applying spectroscopic ellipsometry (SE). Dominant wurtzite phase MZO thin films with Mg contents in the range 0 ≤ x ≤ 0.42 were deposited on room temperature soda lime glass (SLG) substrates by magnetron co-sputtering of MgO and ZnO targets followed by annealing. The complex dielectric functions ε of these films were determined and parameterized over the photon energy range from 0.73 to 6.5 eV using an analytical model consisting of two critical point (CP) oscillators. The CP parameters in this model are expressed as polynomial functions of the best fitting lowest CP energy or bandgap E0 = Eg, which in turn is a quadratic function of x. As functions of x, both the lowest energy CP broadening and the Urbach parameter show minima for x ~ 0.3, which corresponds to a bandgap of 3.65 eV. As a result, it is concluded that for this composition and bandgap, the MZO exhibits either a minimum concentration of defects in the bulk of the crystallites or a maximum in the grain size, an observation consistent with measured X-ray diffraction line broadenings. The parametric expression for ε developed here is expected to be useful in future mapping and through-the-glass SE analyses of partial and complete PV device structures incorporating MZO.

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“…Infrared spectroscopic ellipsometry (IR-SE) data spanning the photon energy range of 0.05 eV to 0.8 eV were acquired and analyzed. [7] Table 3 presents the free carrier parameters as determined from IR-SE data analysis. From ex-situ IR-SE analysis, the enhanced conductivity of the CIS layer due to nitrogen doping could be detected.…”

Section: De-ee0005405mentioning

confidence: 99%

“…[1][2][3] [2] We developed improved methods for process control and monitoring during deposition of the materials we tested. [7,16] We showed that we could determine the current flow pathways in CdTe devices using scanning microwave impedance microscopy, which advances the general understanding of the devices [13,14]. We developed new understanding of electron beam induced current (EBIC) measurements of the devices.…”

Section: Conclusion Of This Workmentioning

confidence: 99%

Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report

Rockett

Marsillac

Collins

2018

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This program has explored a number of novel materials for contacts to CdTe solar cells in order to reduce the back contact Schottky barrier to zero and produce an ohmic contact. The project tested a wide range of potential contact materials including TiN, ZrN, CuInSe2:N, a-Si:H and alloys with C, and FeS2. Improved contacts were achieved with FeS2. As part of understanding the operation of the devices and controlling the deposition processes, a number of other important results were obtained. In the process of this project and following its conclusion it led to research that resulted in seven journal articles, nine conference publications, 13 talks presented at conferences, and training of eight graduate students. The seven journal articles were published in 2015, 2016, and 2017 and have been cited, as of March 2018, 52 times (one cited 19 times and two cited 11 times).

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Multichannel spectroscopic ellipsometry for CdTe Photovoltaics: From real-time monitoring to large-scale mapping

Cited by 3 publications

References 8 publications

Substrate configuration, bifacial CdTe solar cells grown directly on transparent single wall carbon nanotube back contacts

Substrate configuration, bifacial CdTe solar cells grown directly on transparent single wall carbon nanotube back contacts

Optical Properties of Magnesium-Zinc Oxide for Thin Film Photovoltaics

Novel Contact Materials for Improved Performance CdTe Solar Cells Final Report

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