Browsing by Author "Palekis, V."

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    CdTe films by Elemental Vapor Transport [Articol]
    (IEEE, 2013) Kendre, V.; Evani, V.; Khan, M.; Palekis, V.; Vatavu, Sergiu; Morel, D.; Ferekides, C.
    The electro-optical properties of CdTe films deposited by Elemental Vapor Transport (EVT) are being investigated. The EVT process, unlike most processes currently used for the deposition of CdTe thin films, allows for the creation of excess Cd or excess Te conditions during the deposition, which can be used to influence the formation of defects and improve doping in CdTe. Using resistivity measurements, it has been demonstrated that the Cd/Te ratio used during the deposition process influences the incorporation of Cu in CdTe. Photoluminescence measurements have shown that the Cd/Te ratio also influences the formation of defect complexes in CdTe. Junctions formed with CdS suggest that the conductivity of CdTe can be adjusted p- or n-type by creating Te or Cd-rich conditions respectively. Structurally, the EVT-CdTe films have been found to be densely packed and highly oriented.
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    Stoichiometric effects in polycrystalline CdTe [Articol]
    (IEEE, 2014) Khan, M.; Evani, V.; Collins, S.; Palekis, V.; Bane, P.; Bakhshi, S.; Kendre, V.; Vatavu, Sergiu; Morel, D.; Ferekides, C.
    The effect of the vapor phase Cadmium (Cd) to Tellurium (Te) ratio on the electronic properties of CdTe films is being studied. The stoichiometry of CdTe films is being altered by varying the gas phase Cd/Te ratio during the Elemental Vapor Transport (EVT) deposition process. Resistivity-temperature measurements and solar cells made with polycrystalline EVT-CdTe suggest changes in the native cadmium vacancy (V Cd ) concentration and carrier lifetime. The findings are in good agreement with the recently updated defect levels using the HSE approximation. Photoluminescence (PL) analysis has also demonstrated variation in the formation of defect complexes with the Cd/Te ratio. 2-Photon TRPL lifetime measurements showed improved minority-carrier lifetime for CdCl 2 treated samples deposited at low Cd/Te ratios.