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Title: Low-Cost III-V Photovoltaic Materials by Chloride Vapor Transport Deposition Using Safe Solid Precursors

Abstract

Si-based photovoltaic devices dominate the market. As photovoltaic (PV) manufacturing costs have plummeted, technologies which increase efficiency have become critical. Si cell efficiencies are nearing theoretical limits and Si-based PV modules are unlikely to reach the 25-30% efficiency range. The use of III-V semiconductors is an obvious technical solution to improve efficiency, especially if they can be integrated directly with existing Si technology as tandems. High coefficients of light absorption along with tunable bandgaps and lattice constants have resulted in record conversion efficiencies for both one-sun and concentrator PV applications. GaAs, for example, has been used to manufacture single-junction photovoltaics with world-record efficiencies of 28.8% at one sun.2 However, costs for III-Vs must be dramatically reduced to produce cost-effective, high-efficiency PV solutions. III-V costs are controlled by two factors: semiconductor growth and the substrate. III-V growth is dominated today by metal-organic vapor phase epitaxy (MOVPE) with a lesser role played by molecular beam epitaxy (MBE). MOVPE costs are high due to the expense and low utilization (~30%) of precursors, modest growth rates (~100 nm min -1), equipment complexity, and safety infrastructure needed to handle toxic, pyrophoric gases.3 MBE costs are high due to slow growth rates and limitations of scalability.more » Details comparing plausible low-cost III-V growth methods are available in a review article published as a result of this project. The primary goal of this project was to demonstrate that close-spaced vapor transport (CSVT) using chloride (from HCl) as a transport agent can be used for the rapid growth of device-ready III-V layers from safe, solid-source precursors. In pursuit of this goal, we designed, built, and installed a new Cl-CSVT reactor based on insights from our previous H 2O-CSVT growth system and in collaboration with equipment professionals at Malachite Technologies. This system was successfully used to grow epitaxial GaAs with controlled n-type doping, having mobilities similar to MOVPE. Detailed technical information and results can also be found in the primary publication resulting from this project. This work sets the stage for tackling the development of high-performance III-V single junctions and tandem devices directly on Si substrates, which was beyond the capabilities of our H2O-CSVT system. The design of the reactor’s source and substrate transfer system should allow for direct deposition of device structures. The collective innovations of our Cl-CSVT system might ultimately serve as an enabling process for commercialization of the technology through a collaboration with appropriate industrial partners.« less

Authors:
 [1];  [2];  [3]
  1. Univ. of Oregon, Eugene, OR (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Malachite Technologies Inc., San Francisco, CA (United States)
Publication Date:
Research Org.:
Univ. of Oregon, Eugene, OR (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Malachite Technologies Inc., San Francisco, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1455018
Report Number(s):
DOE-UOregon-FTR_5
DOE Contract Number:  
EE0007361
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Boettcher, Shannon, Aloni, Shaul, and Weiss, Robert. Low-Cost III-V Photovoltaic Materials by Chloride Vapor Transport Deposition Using Safe Solid Precursors. United States: N. p., 2018. Web. doi:10.2172/1455018.
Boettcher, Shannon, Aloni, Shaul, & Weiss, Robert. Low-Cost III-V Photovoltaic Materials by Chloride Vapor Transport Deposition Using Safe Solid Precursors. United States. doi:10.2172/1455018.
Boettcher, Shannon, Aloni, Shaul, and Weiss, Robert. Wed . "Low-Cost III-V Photovoltaic Materials by Chloride Vapor Transport Deposition Using Safe Solid Precursors". United States. doi:10.2172/1455018. https://www.osti.gov/servlets/purl/1455018.
@article{osti_1455018,
title = {Low-Cost III-V Photovoltaic Materials by Chloride Vapor Transport Deposition Using Safe Solid Precursors},
author = {Boettcher, Shannon and Aloni, Shaul and Weiss, Robert},
abstractNote = {Si-based photovoltaic devices dominate the market. As photovoltaic (PV) manufacturing costs have plummeted, technologies which increase efficiency have become critical. Si cell efficiencies are nearing theoretical limits and Si-based PV modules are unlikely to reach the 25-30% efficiency range. The use of III-V semiconductors is an obvious technical solution to improve efficiency, especially if they can be integrated directly with existing Si technology as tandems. High coefficients of light absorption along with tunable bandgaps and lattice constants have resulted in record conversion efficiencies for both one-sun and concentrator PV applications. GaAs, for example, has been used to manufacture single-junction photovoltaics with world-record efficiencies of 28.8% at one sun.2 However, costs for III-Vs must be dramatically reduced to produce cost-effective, high-efficiency PV solutions. III-V costs are controlled by two factors: semiconductor growth and the substrate. III-V growth is dominated today by metal-organic vapor phase epitaxy (MOVPE) with a lesser role played by molecular beam epitaxy (MBE). MOVPE costs are high due to the expense and low utilization (~30%) of precursors, modest growth rates (~100 nm min-1), equipment complexity, and safety infrastructure needed to handle toxic, pyrophoric gases.3 MBE costs are high due to slow growth rates and limitations of scalability. Details comparing plausible low-cost III-V growth methods are available in a review article published as a result of this project. The primary goal of this project was to demonstrate that close-spaced vapor transport (CSVT) using chloride (from HCl) as a transport agent can be used for the rapid growth of device-ready III-V layers from safe, solid-source precursors. In pursuit of this goal, we designed, built, and installed a new Cl-CSVT reactor based on insights from our previous H2O-CSVT growth system and in collaboration with equipment professionals at Malachite Technologies. This system was successfully used to grow epitaxial GaAs with controlled n-type doping, having mobilities similar to MOVPE. Detailed technical information and results can also be found in the primary publication resulting from this project. This work sets the stage for tackling the development of high-performance III-V single junctions and tandem devices directly on Si substrates, which was beyond the capabilities of our H2O-CSVT system. The design of the reactor’s source and substrate transfer system should allow for direct deposition of device structures. The collective innovations of our Cl-CSVT system might ultimately serve as an enabling process for commercialization of the technology through a collaboration with appropriate industrial partners.},
doi = {10.2172/1455018},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {4}
}