1.7eV Al0.2Ga0.8As solar cells epitaxially grown on silicon by SSMBE using a superlattice and dislocation filters

Arthur Onno, Jiang Wu, Qi Jiang, Siming Chen, Mingchu Tang, Yurii Maidaniuk, Mourad Benamara, Yuriy I. Mazur, Gregory J. Salamo, Nils Peter Harder, Lars Oberbeck, Huiyin Liu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations

Abstract

Lattice-mismatched 1.7eV Al0.2Ga0.8As photovoltaic solar cells have been monolithically grown on Si substrates using Solid Source Molecular Beam Epitaxy (SSMBE). As a consequence of the 4%-lattice-mismatch, threading dislocations (TDs) nucleate at the interface between the Si substrate and III-V epilayers and propagate to the active regions of the cell. There they act as recombination centers and degrade the performances of the cell. In our case, direct AlAs/GaAs superlattice growth coupled with InAlAs/AlAs strained layer superlattice (SLS) dislocation filter layers (DFLSs) have been used to reduce the TD density from 1×109cm-2 to 1(±0.2)×107cm-2. Lattice-matched Al0.2Ga0.8As cells have also been grown on GaAs as a reference. The best cell grown on silicon exhibits a Voc of 964mV, compared with a Voc of 1128mV on GaAs. Fill factors of respectively 77.6% and 80.2% have been calculated. Due to the lack of an anti-reflection coating and the non-optimized architecture of the devices, relatively low Jsc have been measured: 7.30mA.cm-2 on Si and 6.74mA.cm-2 on GaAs. The difference in short-circuit currents is believed to be caused by a difference of thickness between the samples due to discrepancies in the calibration of the MBE prior to each growth. The bandgap-voltage offset of the cells, defined as Eg/q-Voc, is relatively high on both substrates with 736mV measured on Si versus 572mV on GaAs. The non-negligible TD density partly explains this result on Si. On GaAs, non-ideal growth conditions are possibly responsible for these suboptimal performances.

Original languageEnglish (US)
Title of host publicationPhysics, Simulation, and Photonic Engineering of Photovoltaic Devices V
EditorsMasakazu Sugiyama, Alexandre Freundlich, Laurent Lombez
PublisherSPIE
ISBN (Electronic)9781628419788
DOIs
StatePublished - 2016
Externally publishedYes
EventPhysics, Simulation, and Photonic Engineering of Photovoltaic Devices V - San Francisco, United States
Duration: Feb 15 2016Feb 17 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9743
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferencePhysics, Simulation, and Photonic Engineering of Photovoltaic Devices V
CountryUnited States
CitySan Francisco
Period2/15/162/17/16

Keywords

  • AlGaAs solar cell
  • Dislocation filter
  • III-V on silicon
  • MBE
  • Superlattice
  • Threading dislocation density

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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