Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates

Martín García, Isidro and Alcañiz, A. and Jiménez Pagán, Alba and López, G. and Cañizo Nadal, Carlos del and Datas Medina, Alejandro (2020). Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates. "IEEE Journal of Photovoltaics", v. 10 (n. 4); pp. 1068-1075. ISSN 2156-3381. https://doi.org/10.1109/JPHOTOV.2020.2981839.

Description

Title: Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates
Author/s:
  • Martín García, Isidro
  • Alcañiz, A.
  • Jiménez Pagán, Alba
  • López, G.
  • Cañizo Nadal, Carlos del
  • Datas Medina, Alejandro
Item Type: Article
Título de Revista/Publicación: IEEE Journal of Photovoltaics
Date: July 2020
ISSN: 2156-3381
Volume: 10
Subjects:
Freetext Keywords: Germanium, QSS-PC, minority carrier lifetime
Faculty: Instituto de Energía Solar (IES) (UPM)
Department: Electrónica Física, Ingeniería Eléctrica y Física Aplicada
UPM's Research Group: Silicio y Nuevos Conceptos para Células Solares
Creative Commons Licenses: None

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Abstract

Similar to other high quality crystalline absorbers, an accurate knowledge of surface passivation of crystalline Germanium (c-Ge) substrates is crucial for a straightforward improvement of photovoltaic device performance. For crystalline silicon devices, this information is typically obtained by quasi steady state photoconductance (QSS-PC) technique using Sinton WCT-120 tool. In this work, we explore the conditions to adapt this measurement technique to c-Ge substrates. Based on PC-1D simulations, we deduce that a minimum effective lifetime is needed corresponding to an effective diffusion length equal to the substrate thickness. Apart from this, an accurate estimation of the total photogeneration inside the c-Ge sample is also mandatory. This condition implies that the light intensity that impinges onto the sample must be measured with a c-Ge sensor, although the integrated c-Si sensor can be used for high flash intensities. Additionally, the optical factor used to evaluate sample reflectance must be also known, which is determined by measuring robust effective lifetime values under photoconductance decay conditions. Finally, knowledge about carrier mobility in c-Ge is also necessary to translate the measured photoconductance to the corresponding excess carrier density values. Lifetime measurements of passivated c-Ge substrates done by QSS-PC technique are validated by comparing them with the ones obtained by microwave photoconductance technique.

Funding Projects

TypeCodeAcronymLeaderTitle
Government of SpainTEC2017-82305-RUnspecifiedUnspecifiedCELULAS SOLARES CON CONTACTOS POSTERIORES BASADAS EN SUBSTRATOS DELGADOS DE SILICIO CRISTALINO
Government of SpainENE2017-86683-RUnspecifiedUnspecifiedCÉLULAS SOLARES DE BAJO GAP PARA APLICACIONES TERMOFOTOVOLTAICAS DE ALTA TEMPERATURA
Madrid Regional GovernmentS2018/EMT-4308UnspecifiedUnspecifiedMateriales, Dispositivos y Tecnologías para el Desarrollo de la Industria Fotovoltaica.

More information

Item ID: 62770
DC Identifier: http://oa.upm.es/62770/
OAI Identifier: oai:oa.upm.es:62770
DOI: 10.1109/JPHOTOV.2020.2981839
Official URL: https://ieeexplore.ieee.org/document/9063493
Deposited by: Profesor Titular Carlos del Cañizo Nadal
Deposited on: 25 Jun 2020 06:52
Last Modified: 25 Jun 2020 06:52
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