TY - JOUR
T1 - AlGaAsP Distributed Bragg Reflectors for GaAsP/Si Solar Cells
AU - Li, Brian
AU - Wang, Yiteng
AU - Birge, Adrian
AU - Kim, Bora
AU - Fang, Xizheng
AU - Lee, Minjoo Larry
N1 - Received 8 July 2024; revised 18 September 2024; accepted 8 October 2024. The work of Brian Li was supported by NASA Space Technology Research Fellowship under Grant 80NSSC19K1174. The work of Yiteng Wang and Adrian Birge were supported by the Air Force Office of Scientific Research through the Multidisciplinary University Research Initiative under Award FA9550-23-1-0334. The work of Bora Kim was supported by the Fermi National Accelerator Laboratory and Dr. William Pellico. The work of Xizheng Fang was supported by funding from the Samsung Advanced Institute of Technology. (Corresponding author: Minjoo Larry Lee.) The authors are with the University of Illinois Urbana-Champaign, Champaign, IL 61820 USA (e-mail: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; mllee@ illinois.edu).
PY - 2024
Y1 - 2024
N2 - We investigate (Al)GaAsP distributed Bragg reflectors (DBRs) on Si (001) to improve the quantum efficiency (QE) of 1.7 eV GaAsP solar cells in GaAsP/Si tandem devices. Samples were grown on Si (001) by molecular beam epitaxy and consisted of a 2.1 μm GaAsP/GaP buffer followed by a ∼2 μm DBR with 20 periods of GaAsP/AlxGa1-xAsP alternating layers. Two different DBR designs were studied with x = 0.4 and x = 0.8, both targeting a peak reflectance wavelength of 700 nm. The average threading dislocation density on the DBRs was 1.4 × 107 cm-2, suitable for high-performance GaAsP cells. The reflectance profiles matched well to simulations, and the GaAsP/Al0.8Ga0.2AsP DBR had a significantly higher peak reflectance and reflectance bandwidth than the GaAsP/Al0.4Ga0.6AsP DBR due to the higher refractive index contrast. QE simulations of GaAsP cells showed an improvement of ∼1 mA/cm2 in short-circuit current density with a DBR, which should enable a ∼5% relative efficiency boost in the GaAsP cell and superior current matching to a Si bottom cell in tandem devices.
AB - We investigate (Al)GaAsP distributed Bragg reflectors (DBRs) on Si (001) to improve the quantum efficiency (QE) of 1.7 eV GaAsP solar cells in GaAsP/Si tandem devices. Samples were grown on Si (001) by molecular beam epitaxy and consisted of a 2.1 μm GaAsP/GaP buffer followed by a ∼2 μm DBR with 20 periods of GaAsP/AlxGa1-xAsP alternating layers. Two different DBR designs were studied with x = 0.4 and x = 0.8, both targeting a peak reflectance wavelength of 700 nm. The average threading dislocation density on the DBRs was 1.4 × 107 cm-2, suitable for high-performance GaAsP cells. The reflectance profiles matched well to simulations, and the GaAsP/Al0.8Ga0.2AsP DBR had a significantly higher peak reflectance and reflectance bandwidth than the GaAsP/Al0.4Ga0.6AsP DBR due to the higher refractive index contrast. QE simulations of GaAsP cells showed an improvement of ∼1 mA/cm2 in short-circuit current density with a DBR, which should enable a ∼5% relative efficiency boost in the GaAsP cell and superior current matching to a Si bottom cell in tandem devices.
KW - Distributed Bragg reflector (DBR)
KW - GaAsP
KW - III-V/Si
KW - molecular beam epitaxy (MBE)
KW - quantum efficiency (QE)
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U2 - 10.1109/JPHOTOV.2024.3483931
DO - 10.1109/JPHOTOV.2024.3483931
M3 - Article
AN - SCOPUS:85209768550
SN - 2156-3381
JO - IEEE Journal of Photovoltaics
JF - IEEE Journal of Photovoltaics
ER -