TY - JOUR
T1 - Electronically Passivated Hole-Blocking Titanium Dioxide/Silicon Heterojunction for Hybrid Silicon Photovoltaics
AU - Man, Gabriel
AU - Schwartz, Jeffrey
AU - Sturm, James Christopher
AU - Kahn, Antoine
N1 - Funding Information:
This work was supported by the DOE Sunshot Grant No. DE-EE0005315. G.M. acknowledges partial financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC). G.M. thanks the Central New Jersey branch of the IEEE for partial financial support of the construction of the TiO
Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2016/8/5
Y1 - 2016/8/5
N2 - Carrier-selective heterojunctions are important for low-cost silicon-based photovoltaic applications. A low temperature (<100 °C) chemical vapor deposition technique is used here to deposit ultrathin (n-type) titanium dioxide (TiO2) layers onto hydrogen-passivated surfaces of crystalline-silicon (c-Si). Energy level alignment and chemical composition at these abrupt, interfacial layer-free TiO2/Si heterojunctions are investigated via ultraviolet, X-ray, and inverse photoemission spectroscopy, for c-Si doping ranging from p++(1019) to n++(1019). The interface Fermi level position and device-relevant TiO2/Si band offsets are found to shift monotonically as a function of the Si doping, revealing the absence of Fermi level pinning at the c-Si interface and pointing to simple Fermi level equilibration as the driving mechanism behind the interface energy level alignment. Electrical transport measurements performed on TiO2/Si-based diodes confirm the energy level alignment yielded by spectroscopic measurements and the hole-blocking properties of the TiO2/Si heterojunction, exclude hole conduction in the TiO2 as a transport mechanism, and show carrier recombination at the TiO2/p-Si heterojunction.
AB - Carrier-selective heterojunctions are important for low-cost silicon-based photovoltaic applications. A low temperature (<100 °C) chemical vapor deposition technique is used here to deposit ultrathin (n-type) titanium dioxide (TiO2) layers onto hydrogen-passivated surfaces of crystalline-silicon (c-Si). Energy level alignment and chemical composition at these abrupt, interfacial layer-free TiO2/Si heterojunctions are investigated via ultraviolet, X-ray, and inverse photoemission spectroscopy, for c-Si doping ranging from p++(1019) to n++(1019). The interface Fermi level position and device-relevant TiO2/Si band offsets are found to shift monotonically as a function of the Si doping, revealing the absence of Fermi level pinning at the c-Si interface and pointing to simple Fermi level equilibration as the driving mechanism behind the interface energy level alignment. Electrical transport measurements performed on TiO2/Si-based diodes confirm the energy level alignment yielded by spectroscopic measurements and the hole-blocking properties of the TiO2/Si heterojunction, exclude hole conduction in the TiO2 as a transport mechanism, and show carrier recombination at the TiO2/p-Si heterojunction.
KW - Fermi level unpinning
KW - carrier-selective heterojunction
KW - heterocontact
KW - heterointerfaces
KW - silicon
KW - titanium dioxide
UR - http://www.scopus.com/inward/record.url?scp=84982061641&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84982061641&partnerID=8YFLogxK
U2 - 10.1002/admi.201600026
DO - 10.1002/admi.201600026
M3 - Article
AN - SCOPUS:84982061641
SN - 2196-7350
VL - 3
JO - Advanced Materials Interfaces
JF - Advanced Materials Interfaces
IS - 15
M1 - 1600026
ER -