The Bridge - Issue 2, 2021 - 31

Feature
A Review of Schottky Junction Solar Cells
approach, the electric field that is generated by the
fixed negative charges, existing at the interface of the
passivation layer and the n-GaAs semiconductor layer,
keeps the free charge carriers away from the surface
of the semiconductor where they can be trapped and
non-radiatively recombined.
Figure 8. Current-voltage
characteristics of metal/nGaAs
Schottky junction solar
cells without and with Al2
O3
passivation layer. Inset shows
the zoomed-in currentvoltage
characteristics in the
forward voltage region [18].
REFERENCES
[1] J. Rogelj, M. den Elzen, N. Hihne, T. Fransen, H. Fekete, H.
Winkler, R. Schaeffer, F. Sha, K. Riahi, and M. Meinshausen, " Paris
Agreement Climate Proposal Need a Boost to Keep Warming
Below 2 °C " Nature, 534, 631-639 (2016).
[2] U.S energy Information Administration, Monthly Energy Review,
[Online] (2019).
[3] M. A. Green, " Enhancement of Schotty Solar Cell Efficiency
Above its Semiempirical limit " , Appl. Phys. Lett., 27, 287-288
(1975).
[4] W. Shockley, " The Shockley-Queisser Limit " , J. Appl. Phys., 32,
510-519 (1961).
[5] Fraunhofer Institute for Solar Energy Systems, Photovoltaic
Report. [Online] (2020).
[6] J. K. Sim, S. Kang, R. Nandi, J. Y. Jo, K. U. Jeong, and C. R. Lee,
" Implementation of Graphene as Hole Transport Electrode in
Flexible CIGS Solar Cells Fabricated on Cu Foil " , Solar Energy, 162,
357-363 (2018).
Ultrathin films of Al2
O3 were grown using atomic
layer deposition and used as the passivation layer
in this structure. Figure 8 shows the current-voltage
characteristics of the metal/n-GaAs Schottky junction
solar cells without and with the Al2
O3
passivation. A
notable reduction in the leakage current in the reverse
voltage region, in addition to an increase in the opencircuit
voltage is observed for the passivated solar cell.
The proposed strategy shows the effectiveness of the
passivation layer to improve both the diode-like and
photovoltaic properties of the Schottky solar cells [18].
IV. SUMMARY AND CONCLUSIONS
Recent advances in design and fabrication of high
efficiency solar cells have focused on semiconductor
materials beyond silicon, and structures beyond p-n
junction. Schottky junction solar cells, which are based
on the interface of a thin conducting film with a high
work function and a semiconductor layer, are receiving
much attention due to their ability to produce a
reasonable power conversion efficiency. Additionally,
a simple and cost-effective fabrication process, makes
the Schottky junction solar cells suitable for use in
large-scale photovoltaic devices. However, a narrower
depletion region width and higher leakage current,
reduces the overall power conversion efficiency of
Schottky solar cells compared to p-n junction solar cells.
Recent studies have shown that surface passivation
is an effective approach in reducing the density of
surface defects at or close to the metal-semiconductor
interface, which eventually, results into improved diodelike
and photovoltaic properties of Schottky junction
solar cells.
[7] T. Kato, J. L. Wu, Y. Hirai, H. Sugimoto, and V. Bermudez,
" Record Efficienct for Thin-Film Polycrystalline Solar Cells Up
to 22.9% Achieved by Cs-Treated Cu(In,Ge)(Se,S)2 " , IEEE J.
Photovolt., 9, 325-330 (2019).
[8] First Solar, " First Solar Builds the Higher Efficiency Thin Film PV
Cell on Record " [Online], 2014, Accessed June 30 2019.
[9] V. M. Fthenakis, " Life Cylce Impact Analysis of Cadmium in
CdTe PV Production " , Renew. Sustain. Energy Rev., 8, 303-334
(2004).
[10] W. Zhao, S. Li, H. Yao, S. Zhang, Y. Zhang, B. Yang, and J. Hou,
" Molecular Optimization Enables Over 13% Efficiency in Organic
Solar Cells " , J. Am. Chem. Soc., 139, 7148-7151 (2017).
[11] Chris G. Van de Walle and J. Neugebauer, " Defect, Impurities
and Doping Levels in Wide-Band-Gap Semiconductors " , Brazil. J.
Phys., 26, 163-168 (1996).
[12] J. L. Lyons, A. Janotti, and C. G. Van de Walle, " Effects of Hole
Localization on Limiting p-type Conductivity in Oxide and Nitride
Semiconductors " , J. Appl. Phys., 115, 012014 (2014).
[13] D. Pulfrey, " MIS Solar Cells: A Review " , IEEE Trans. Electron.
Dev., 25, 1308-1317 (1978).
[14] H. S. Kim et al., " Indium-Tin-Oxide/GaAs Schottky Barrier
Solar Cells with Embedded InAs Quantum Dots " , Thin Sol. Films,
604, 81-84 (2016).
[15] H. He et al., " 13.7% Efficiency Graphene-Gallium Arsenide
Schottky Junction Solar Cells with a P3HT Hole Transport Layer " ,
Nano Energy, 16, 91-98 (2015).
[16] A. Turut et al., " Capacitance-Conduction-Current-Voltage
Characteristics of Atomic Layer Deposited Au/Ti/Al2
O3/n-GaAs
MIS Structures " , Mater. Sci. Semicond. Process., 39, 400-407
(2015).
[17] A. Alnuaimi et al., " Interface Engineering of Graphene-Silicon
Schottky Junction Solar Cells with an Al2O3 Interfacial Layer
Grown by Atomic Layer Deposition " , RSC Adv., 8, 10593-10597
(2018).
[18] A. Ghods, V. G. Saravade, C. Zhou, and I. T. Ferguson, " FieldEffect
Passivation of Metal/n-GaAs Schottky Junction Solar Cells
Using Atomic Layer Deposited Al2O3/ZnO Ultrathin films " , J. Vac.
Sci. Technol., 38, 012406 (2020).
HKN.ORG
31
https://www.eia.gov/energyexplained/renewable-sources/ https://www.ise.fraunhofer.de/content/dam/ise/de/documents/publications/studies/Photovoltaics-Report.pdf https://investor.firstsolar.com/news/press-release-details/2014/First-Solar-Builds-the-Highest-Efficiency-Thin-Film-PV-Cell-on-Record/default.aspx https://hkn.ieee.org/ https://hkn.ieee.org/
The Bridge - Issue 2, 2021

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