Performance analysis of AlGaAs/GaAs tunnel junctions for ultra-high concentration photovoltaics

García Vara, Iván and Rey-Stolle Prado, Ignacio and Algora del Valle, Carlos (2012). Performance analysis of AlGaAs/GaAs tunnel junctions for ultra-high concentration photovoltaics. "Journal of Physics D: Applied Physics", v. 45 (n. 4); pp. 45101-45108. ISSN 0022-3727. https://doi.org/10.1088/0022-3727/45/4/045101.

Description

Title: Performance analysis of AlGaAs/GaAs tunnel junctions for ultra-high concentration photovoltaics
Author/s:
  • García Vara, Iván
  • Rey-Stolle Prado, Ignacio
  • Algora del Valle, Carlos
Item Type: Article
Título de Revista/Publicación: Journal of Physics D: Applied Physics
Date: January 2012
ISSN: 0022-3727
Volume: 45
Subjects:
Faculty: E.T.S.I. Telecomunicación (UPM)
Department: Electrónica Física
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

An n(++)-GaAs/p(++)-AlGaAs tunnel junction with a peak current density of 10 100Acm(-2) is developed. This device is a tunnel junction for multijunction solar cells, grown lattice-matched on standard GaAs or Ge substrates, with the highest peak current density ever reported. The voltage drop for a current density equivalent to the operation of the multijunction solar cell up to 10 000 suns is below 5 mV. Trap-assisted tunnelling is proposed to be behind this performance, which cannot be justified by simple band-to-band tunnelling. The metal-organic vapour-phase epitaxy growth conditions, which are in the limits of the transport-limited regime, and the heavy tellurium doping levels are the proposed origins of the defects enabling trap-assisted tunnelling. The hypothesis of trap-assisted tunnelling is supported by the observed annealing behaviour of the tunnel junctions, which cannot be explained in terms of dopant diffusion or passivation. For the integration of these tunnel junctions into a triple-junction solar cell, AlGaAs barrier layers are introduced to suppress the formation of parasitic junctions, but this is found to significantly degrade the performance of the tunnel junctions. However, the annealed tunnel junctions with barrier layers still exhibit a peak current density higher than 2500Acm(-2) and a voltage drop at 10 000 suns of around 20 mV, which are excellent properties for tunnel junctions and mean they can serve as low-loss interconnections in multijunction solar cells working at ultra-high concentrations.

More information

Item ID: 15404
DC Identifier: http://oa.upm.es/15404/
OAI Identifier: oai:oa.upm.es:15404
DOI: 10.1088/0022-3727/45/4/045101
Official URL: http://iopscience.iop.org/0022-3727/45/4/045101/article
Deposited by: Memoria Investigacion
Deposited on: 29 May 2013 16:50
Last Modified: 21 Apr 2016 15:27
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