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

Title: Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance

Abstract

This paper discusses recent efforts to realize GaInAsSb/GaSb TPV cells with an internal back-surface reflector (BSR). The cells are fabricated by wafer bonding the GaInAsSb/GaSb device layers to GaAs substrates with a dielectric/Au reflector, and subsequently removing the GaSb substrate. The internal BSR enhances optical absorption within the device while the dielectric layer provides electrical isolation. This approach is compatible with monolithic integration of series-connected TPV cells and can mitigate the requirements of filters used for front-surface spectral control.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lockheed Martin Corporation, Schenectady, NY 12301 (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
821703
Report Number(s):
LM-02K065
TRN: US200411%%685
DOE Contract Number:
AC12-00SN39357
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 12 Aug 2002
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; ABSORPTION; BONDING; DIELECTRIC MATERIALS; PERFORMANCE; SUBSTRATES

Citation Formats

C.A. Wang, P.G. Murphy, P.W. O'Brien, D.A. Shiau, A.C. Anderson, Z.L. Liau, D.M. Depoy, and G. Nichols. Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance. United States: N. p., 2002. Web. doi:10.2172/821703.
C.A. Wang, P.G. Murphy, P.W. O'Brien, D.A. Shiau, A.C. Anderson, Z.L. Liau, D.M. Depoy, & G. Nichols. Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance. United States. doi:10.2172/821703.
C.A. Wang, P.G. Murphy, P.W. O'Brien, D.A. Shiau, A.C. Anderson, Z.L. Liau, D.M. Depoy, and G. Nichols. 2002. "Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance". United States. doi:10.2172/821703. https://www.osti.gov/servlets/purl/821703.
@article{osti_821703,
title = {Wafer-Bonded Internal Back-Surface Reflectors for Enhanced TPV Performance},
author = {C.A. Wang and P.G. Murphy and P.W. O'Brien and D.A. Shiau and A.C. Anderson and Z.L. Liau and D.M. Depoy and G. Nichols},
abstractNote = {This paper discusses recent efforts to realize GaInAsSb/GaSb TPV cells with an internal back-surface reflector (BSR). The cells are fabricated by wafer bonding the GaInAsSb/GaSb device layers to GaAs substrates with a dielectric/Au reflector, and subsequently removing the GaSb substrate. The internal BSR enhances optical absorption within the device while the dielectric layer provides electrical isolation. This approach is compatible with monolithic integration of series-connected TPV cells and can mitigate the requirements of filters used for front-surface spectral control.},
doi = {10.2172/821703},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2002,
month = 8
}

Technical Report:

Save / Share:
  • A novel implementation for GAInAsSb/AlGaAsSb/GaSb TPV cells with an internal back-surface reflector (BSR) formed by wafer bonding to GaAs is demonstrated. The SiO{sub x}/Ti/Au internal BSR enhances optical absorption within the device, while the dielectric layer provides electrical isolation. This configuration has the potential to improve TPV device performance; is compatible with monolithic series-interconnection of TPV cells for building voltage; and can mitigate the requirements of filters used for front-surface spectral control. At a short-circuit density of 0.4 A/cm{sup 2}, the open-circuit voltage of a single TPV cell is 0.2 V, compared to 0.37 and 1.8 V for 2- andmore » 10-junction series-interconnected TPV cells, respectively.« less
  • Amorphous silicon (a-Si) and amorphous silicon nitride (a-SiN{sub x}) layers deposited by magnetron sputtering have been analyzed in order to determine their optical and surface properties. A large value of {approx}1.9 of index difference is found between these materials. Distributed Bragg reflectors (DBRs) based on these dielectric material quarter wave layers have been studied by optical measurements and confronted to theoretical calculations based on the transfer matrix method. A good agreement has been obtained between the experimental and expected reflectivities. A maximum reflectivity of 99.5% at 1.55 {mu}m and a large spectral bandwidth of 800 nm are reached with onlymore » four and a half periods of a-Si/a-SiN{sub x}. No variation of the DBR reflectivity has been observed with the time nor when annealed above 240 deg. C and stored during few months. This result allows us to use this DBR in a metallic bonding process to realize a vertical cavity surface emitting laser (VCSEL) with two dielectric a-Si/a-SiN{sub x} DBRs. This bonding method using AuIn{sub 2} as the bonding medium and Si substrate can be performed at a low temperature of 240 deg. C without damaging the optical properties of the microcavity. The active region used for this VCSEL is based on lattice-matched InGaAs/InGaAsP quantum wells and a laser emission has been obtained at room temperature on an optically pumped device.« less
  • The Wafer Test cavity was designed to create a short sample test system to determine the properties of the superconducting materials and S-I-S hetero-structures. The project, funded by ARRA, was successful in accomplishing several goals to achieving a high gradient test system for SRF research and development. The project led to the design and construction of the two unique cavities that each severed unique purposes: the Wafer test Cavity and the Sapphire Test cavity. The Sapphire Cavity was constructed first to determine the properties of large single crystal sapphires in an SRF environment. The data obtained from the cavity greatlymore » altered the design of the Wafer Cavity and provided the necessary information to ascertain the Wafer Test cavity’s performance.« less
  • NREL and MEMC Electronic Materials are interested in developing a robust technique for monitoring material quality of mc-Si and mono-Si wafers -- a technique that can provide relevant data to accurately predict the performance of solar cells fabricated on them. Previous work, performed under two TSAs between NREL and MEMC, has established that dislocation clusters are the dominant performance-limiting factor in MEMC mc-Si solar cells. The work under this CRADA will go further in verifying these results on a larger data set, evaluate possibilities of faster method(s) for mapping dislocations in wafers/ingots, understanding dislocation generation during ingot casting, and helpingmore » MEMC to have an internal capability for basic characterization that will provide feedback needed for more accurate crystallization simulations. NREL has already developed dislocation mapping technique and developed a basic electronic model (called Network Model) that uses spatial distribution of dislocations to predict the cell performance. In this CRADA work, we will use these techniques to: (i) establish dislocation, grain size, and grain orientation distributions of the entire ingots (through appropriate DOE) and compare these with theoretical models developed by MEMC, (ii) determine concentrations of some relevant impurities in selected wafers, (iii) evaluate potential of using photoluminescence for dislocation mapping and identification of recombination centers, (iv) evaluate use of diode array analysis as a detailed characterization tool, and (v) establish dislocation mapping as a wafer-quality monitoring tool for commercial mc-Si production.« less
  • For the sake of good optical efficiency, the reflectivity rho of mirror surfaces in solar collectors should be as high as possible. Until now, most solar reflectors have used aluminum with values of rho in the 80 to 90 percent range. Even the best material, silver, allows reflectivities only up to 95 percent. With total internal reflection (TIR), on the other hand, the effective reflectivity is limited only by absorption in the transparent medium, and absorption losses can as easily be kept below five percent. In certain solar collectors, conventional mirrors can be replaced by an array of small rectangularmore » glass prisms, an optical trick well known from binoculars. The only problem is that TIR occurs for a restricted range of incidence angles, limited by the low value of the refractive index n approximately equal to 1.5 of commonly available glass or acrylic. However, an additional degree of freedom is gained in the design of solar collectors because only concentration, not imaging, is relevant. The suitability of TIR prismatic reflectors for solar energy collection is investigated systematically. (WDM)« less