skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tunnel Junction Development Using Hydride Vapor Phase Epitaxy

Abstract

We demonstrate for the first time III-V tunnel junctions grown using hydride vapor phase epitaxy (HVPE) with peak tunneling currents >8 A/cm 2, sufficient for operation of a multijunction device to several hundred suns of concentration. Multijunction solar cells rely on tunneling interconnects between subcells to enable series connection with minimal voltage loss, but tunnel junctions have never been shown using the HVPE growth method. HVPE has recently reemerged as a low-cost growth method for high-quality III-V materials and devices, including the growth of high-efficiency III-V solar cells. We previously showed single-junction GaAs solar cells with conversion efficiencies of ~24% with a path forward to equal or exceed the practical efficiency limits of crystalline Si. Moving to a multijunction device structure will allow for even higher efficiencies with minimal impact on cost, necessitating the development of tunnel interconnects. Here in this paper, we demonstrate the performance of both isolated HVPE-grown tunnel junctions, as well as single-junction GaAs solar cell structures with a tunnel junction incorporated into the contact region. We observe no degradation in device performance compared to a structure without the added junction.

Authors:
 [1];  [1];  [1];  [1]
  1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1406185
Report Number(s):
NREL/JA-5J00-68632
Journal ID: ISSN 2156-3381
Grant/Contract Number:
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2156-3381
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; gallium arsenide; hydride vapor phase epitaxy; photovoltaics; tunnel junctions

Citation Formats

Ptak, Aaron J., Simon, John D., Schulte, Kevin L., and Jain, Nikhil. Tunnel Junction Development Using Hydride Vapor Phase Epitaxy. United States: N. p., 2017. Web. doi:10.1109/JPHOTOV.2017.2756566.
Ptak, Aaron J., Simon, John D., Schulte, Kevin L., & Jain, Nikhil. Tunnel Junction Development Using Hydride Vapor Phase Epitaxy. United States. doi:10.1109/JPHOTOV.2017.2756566.
Ptak, Aaron J., Simon, John D., Schulte, Kevin L., and Jain, Nikhil. 2017. "Tunnel Junction Development Using Hydride Vapor Phase Epitaxy". United States. doi:10.1109/JPHOTOV.2017.2756566.
@article{osti_1406185,
title = {Tunnel Junction Development Using Hydride Vapor Phase Epitaxy},
author = {Ptak, Aaron J. and Simon, John D. and Schulte, Kevin L. and Jain, Nikhil},
abstractNote = {We demonstrate for the first time III-V tunnel junctions grown using hydride vapor phase epitaxy (HVPE) with peak tunneling currents >8 A/cm2, sufficient for operation of a multijunction device to several hundred suns of concentration. Multijunction solar cells rely on tunneling interconnects between subcells to enable series connection with minimal voltage loss, but tunnel junctions have never been shown using the HVPE growth method. HVPE has recently reemerged as a low-cost growth method for high-quality III-V materials and devices, including the growth of high-efficiency III-V solar cells. We previously showed single-junction GaAs solar cells with conversion efficiencies of ~24% with a path forward to equal or exceed the practical efficiency limits of crystalline Si. Moving to a multijunction device structure will allow for even higher efficiencies with minimal impact on cost, necessitating the development of tunnel interconnects. Here in this paper, we demonstrate the performance of both isolated HVPE-grown tunnel junctions, as well as single-junction GaAs solar cell structures with a tunnel junction incorporated into the contact region. We observe no degradation in device performance compared to a structure without the added junction.},
doi = {10.1109/JPHOTOV.2017.2756566},
journal = {IEEE Journal of Photovoltaics},
number = 1,
volume = 8,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on October 18, 2018
Publisher's Version of Record

Save / Share:
  • Hydride vapor phase epitaxy (HVPE) is a low-cost alternative to conventional metal-organic vapor phase epitaxy (MOVPE) growth of III-V solar cells. In this work, we show continued improvement of the performance of HVPE-grown single-junction GaAs solar cells. We show over an order of magnitude improvement in the interface recombination velocity between GaAs and GaInP layers through the elimination of growth interrupts, leading to increased short-circuit current density and open-circuit voltage compared with cells with interrupts. One-sun conversion efficiencies as high as 20.6% were achieved with this improved growth process. Solar cells grown in an inverted configuration that were removed frommore » the substrate showed nearly identical performance to on-wafer cells, demonstrating the viability of HVPE to be used together with conventional wafer reuse techniques for further cost reduction. As a result, these devices utilized multiple heterointerfaces, showing the potential of HVPE for the growth of complex and high-quality III-V devices.« less
  • GaAs tunnel p-n junctions with peak current densities up to 45 A cm/sup -2/ were grown by metallorganic vapor-phase epitaxy. These tunnel diodes are suitable for intercell ohmic contacts between the case of integrated tandem photovoltaic subcells in solar cells based on GaAs. The peak current is high enough for concentration up to C = 1000.
  • The high cost of high-efficiency III-V photovoltaic devices currently limits them to niche markets. Hydride vapor-phase epitaxy (HVPE) growth of III-V materials recently reemerged as a low-cost, high-throughput alternative to conventional metal- organic vapor-phase epitaxy (MOVPE) growth of high-efficiency solar cells. Previously, we demonstrated unpassivated HVPEgrown GaAs p-n junctions with good quantum efficiency and high open-circuit voltage (Voc). In this work, we demonstrate the growth of GaInPby HVPE for use as a high-quality surface passivation layer to GaAs solar cells. Solar cells grown with GaInP window layers show significantly improved quantum efficiency compared with unpassivated cells, increasing the short-circuit currentmore » (JSC) of these low-cost devices. These results show the potential of low-cost HVPE for the growth of high-quality III-V devices.« less
  • We demonstrate the growth of homojunction GaInP solar cells by dynamic hydride vapor phase epitaxy for the first time. Simple unpassivated n-on-p structures grown in an inverted configuration with gold back reflectors were analyzed. Short wavelength performance varied strongly with emitter thickness, since collection in the emitter was limited by the lack of surface passivation. Collection in the base increased strongly with decreasing doping density, in the range 1 x 10 16 - 5 x 10 17 cm -3. Optical modeling indicated that, in our best device, doped ~1 x 10 16 cm -3, almost 94% of photons that passedmore » through the emitter were collected. Modeling also indicated that the majority of collection occurs in the depletion region with this design, suggesting that nonradiative recombination there might limit device performance. In agreement with this observation, the experimental dark J-V curve exhibited an ideality factor near n = 2. Thus, limitation of deep level carrier traps in the material is a path to improved performance. Preliminary experiments indicate that a reduced V/III ratio, which potentially affects the density of these presumed traps, improves cell performance. With reduced V/III ratio, we demonstrate a ~13% efficient GaInP cell measured under the 1-sun AM1.5G spectrum. In conclusion, this cell had an antireflective coating, but no front surface passivation.« less
  • Room-temperature operation was obtained in a new transverse junction stripe laser with distributed feedback. The wafers were grown by a liquid phase epitaxy/metal-organic chemical vapor deposition (LPE/MO-CVD) hybrid technique. These lasers operated stably in a single longitudinal mode at room temperature under pulsed operation. The temperature dependence of lasing wavelength was dlambda/dT = 0.63 A//sup 0/C.