D. Attygalle, V. Ranjan, P. Aryal, P. Pradhan, S. Marsillac, N. Podraza, R. Collins
{"title":"Optical monitoring and control of three-stage coevaporated Cu(In1−xGax)Se2 by real-time spectroscopic ellipsometry","authors":"D. Attygalle, V. Ranjan, P. Aryal, P. Pradhan, S. Marsillac, N. Podraza, R. Collins","doi":"10.1109/pvsc-vol2.2012.6656736","DOIUrl":null,"url":null,"abstract":"Real-time spectroscopic ellipsometry (RTSE) has been applied for in situ monitoring and control of thin-film copper-indium-gallium-diselenide, i.e., Cu(In1−xGax)Se2 (CIGS), deposition by high vacuum coevaporation in the three-stage process used for efficient photovoltaic devices. Initial studies have been performed on a ∼0.7-µm CIGS layer deposited on crystal silicon to minimize surface roughness and to develop an accurate structural/ optical model of the Cu-poor-to-Cu-rich and Cu-rich-to-Cu-poor transitions that define the ends of the second (II) and third (III) stages of growth, respectively.With a better understanding of the surface achieved through this model, correlations can be made between the surface state and the unprocessed RTSE data {ψ(t), Δ(t)}. During deposition in the solar cell configuration with 2- µm-thick CIGS on a Mo-coated glass substrate, indications of the Cu poor-to-rich and Cu rich-to-poor transitions appear clearly in {ψ(t), Δ(t)}, enabling direct control of stage II and III transitions. The transition times deduced optically are in good agreement with those identified from the film/substrate emissivity by tracking the substrate heater power. It is clear, however, that RTSE can provide higher sensitivity to these transitions and is, therefore, suitable for improved control of three-stage CIGS deposition.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"12","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1109/pvsc-vol2.2012.6656736","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 12
Abstract
Real-time spectroscopic ellipsometry (RTSE) has been applied for in situ monitoring and control of thin-film copper-indium-gallium-diselenide, i.e., Cu(In1−xGax)Se2 (CIGS), deposition by high vacuum coevaporation in the three-stage process used for efficient photovoltaic devices. Initial studies have been performed on a ∼0.7-µm CIGS layer deposited on crystal silicon to minimize surface roughness and to develop an accurate structural/ optical model of the Cu-poor-to-Cu-rich and Cu-rich-to-Cu-poor transitions that define the ends of the second (II) and third (III) stages of growth, respectively.With a better understanding of the surface achieved through this model, correlations can be made between the surface state and the unprocessed RTSE data {ψ(t), Δ(t)}. During deposition in the solar cell configuration with 2- µm-thick CIGS on a Mo-coated glass substrate, indications of the Cu poor-to-rich and Cu rich-to-poor transitions appear clearly in {ψ(t), Δ(t)}, enabling direct control of stage II and III transitions. The transition times deduced optically are in good agreement with those identified from the film/substrate emissivity by tracking the substrate heater power. It is clear, however, that RTSE can provide higher sensitivity to these transitions and is, therefore, suitable for improved control of three-stage CIGS deposition.