TY - JOUR
T1 - Silicon Nitride Barrier Layers Mitigate Minority-Carrier Lifetime Degradation in Silicon Wafers during Simulated MBE Growth of III-V Layers
AU - Zhang, Chaomin
AU - Ding, Laura
AU - Boccard, Mathieu
AU - Narland, Tine U.
AU - Faleev, Nikolai
AU - Bowden, Stuart
AU - Bertoni, Mariana
AU - Honsberg, Christiana
AU - Holman, Zachary
N1 - Funding Information:
Manuscript received August 19, 2018; revised November 15, 2018 and December 26, 2018; accepted January 7, 2019. Date of publication January 24, 2019; date of current version February 18, 2019. This work was supported in part by the U.S. Department of Energy under Contract DE-EE0006335 and in part by the Engineering Research Center Program of the National Science Foundation and the Office of Energy Efficiency and Renewable Energy of the Department of Energy under NSF Cooperative Agreement EEC-1041895. (Corresponding author: Chaomin Zhang.) The authors are with Arizona State University, Tempe, AZ 85287 USA (e-mail:, czhang86@asu.edu; Laura.Ding@asu.edu; Mathieu.Boccard@asu. edu; Tine.Naerland@asu.edu; Nikolai.Faleev@asu.edu; sgbowden@asu.edu; bertoni@asu.edu; Christiana.Honsberg@asu.edu; Zachary.Holman@asu.edu).
Publisher Copyright:
© 2011-2012 IEEE.
PY - 2019/3
Y1 - 2019/3
N2 - We observe a degradation of the minority-carrier lifetime in silicon substrates after a temperature cycle in a molecular beam epitaxy (MBE) chamber that is representative of the growth of III-V materials. This decrease in the lifetime is from milliseconds to microseconds, and in some cases into the sub-microsecond range. The degradation appears to be caused by thermally activated diffusion of metals from the back side of the substrate, occurring at temperatures above 500 °C. This impacts the ability to achieve high-performance monolithic III-V/Si multi-junction solar cells, since the epitaxial growth usually requires high-temperature steps (over 700 °C) for surface de-oxidation or surface reconstruction and temperatures of 400-600 °C during the epitaxial growth. We show that, through phosphorous diffusion gettering, the lifetimes of degraded wafers can be recovered to the millisecond range. Further, we demonstrate that a silicon nitride coating functions both as a diffusion barrier and as an interfacial gettering or hydrogenation agent, enabling high minority-carrier lifetimes directly out of the MBE chamber. This approach allows for the silicon minority-carrier lifetime to be maintained in the millisecond range without the need for post-growth recovery, providing a path to achieve high-efficiency III-V/Si solar cells.
AB - We observe a degradation of the minority-carrier lifetime in silicon substrates after a temperature cycle in a molecular beam epitaxy (MBE) chamber that is representative of the growth of III-V materials. This decrease in the lifetime is from milliseconds to microseconds, and in some cases into the sub-microsecond range. The degradation appears to be caused by thermally activated diffusion of metals from the back side of the substrate, occurring at temperatures above 500 °C. This impacts the ability to achieve high-performance monolithic III-V/Si multi-junction solar cells, since the epitaxial growth usually requires high-temperature steps (over 700 °C) for surface de-oxidation or surface reconstruction and temperatures of 400-600 °C during the epitaxial growth. We show that, through phosphorous diffusion gettering, the lifetimes of degraded wafers can be recovered to the millisecond range. Further, we demonstrate that a silicon nitride coating functions both as a diffusion barrier and as an interfacial gettering or hydrogenation agent, enabling high minority-carrier lifetimes directly out of the MBE chamber. This approach allows for the silicon minority-carrier lifetime to be maintained in the millisecond range without the need for post-growth recovery, providing a path to achieve high-efficiency III-V/Si solar cells.
KW - III-V/Si integration
KW - SiN
KW - diffusion barrier
KW - minoritycarrier lifetime
KW - molecular beam epitaxy (MBE)
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U2 - 10.1109/JPHOTOV.2019.2892522
DO - 10.1109/JPHOTOV.2019.2892522
M3 - Article
AN - SCOPUS:85062225961
VL - 9
SP - 431
EP - 436
JO - IEEE Journal of Photovoltaics
JF - IEEE Journal of Photovoltaics
SN - 2156-3381
IS - 2
M1 - 8625581
ER -