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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Inverted Metamorphic Multijunction (IMM) Cell Processing Instructions

This technical report details the processing schedule used to fabricate Inverted Metamorphic Multijunction (IMM) concentrator solar cells at The National Renewable Energy Laboratory (NREL). These devices are used as experimental test structures to support the research at NREL that is focused on increasing the efficiency of photovoltaic power conversion. They are not intended to be devicessuitable for deployment in working concentrator systems primarily because of heat sinking issues. The process schedule was developed to be compatible with small sample sizes and to afford relatively rapid turn-around times, in support of research efforts. The report describes the use of electro deposition of gold for both the back and front contacts. Electro-deposition is used because of itsrapid turn around time and because it is a benign metallization technique that is seldom responsible for damage to the semiconductors. The layer transfer technique is detailed including the use of a commercially available adhesive and the etching away of the parent gallium arsenide substrate. Photolithography is used to define front contact grids as well as the mesa area of the cell. Finally,the selective wet chemical etchant system is introduced and its use to reveal the back contact is described.

14 SOLAR ENERGY↗
DOE OSTI2019

Printed assemblies of microscale triple–junction inverted metamorphic GaInP/GaAs/InGaAs solar cells

Inverted metamorphic (IMM) multijunction solar cells represent a promising material platform for ultrahigh efficiency photovoltaic systems (UHPVs) with a clear pathway to beyond 50% efficiency. The conventional device processing of IMM solar cells, however, typically involves wafer bonding of a centimeter-scale die and destructive substrate removal, thereby imposing severe restrictions in achievable cell size, type of module substrate, spatial layout, as well as cost effectiveness. Here, we report material design and fabrication strategies for microscale triple-junction IMM (3J IMM) Ga 0.51 In 0.49 P/GaAs/In 0.26 Ga 0.74 As solar cells that can overcome these difficulties. Specialized schemes of delineation and undercut etching enable the defect-free release of microscale IMM solar cells and printed assemblies on a glass substrate in a manner that preserves the growth substrate, where efficiencies of 27.3% and 33.9% are demonstrated at simulated AM1.5D one- and 351 sun illumination, respectively. A composite carrier substrate where released IMM microcells are formed in fully functional, print-ready configurations allows high-throughput transfer printing of individual IMM microcells in a programmable spatial layout on versatile choices of module substrate, all desired for CPV applications.

14 SOLAR ENERGY↗
DOE OSTI2018

Printed Assemblies of Microscale Triple-Junction (3J) Inverted Metamorphic (IMM) GaInP/GaAs/InGaAs Solar Cells

Transfer printing of microscale devices has been shown to be a manufacturable pathway to low-profile, low cost, high concentration photovoltaic modules, where extremely high efficiency solar cells are desirable to achieve competitive costs. Inverted metamorphic multijunction (IMM) solar cells represent a promising platform for ultrahigh efficiency concentrator photovoltaic systems with a clear pathway to 50% efficiency. While transfer printing of microscale solar cell devices has been demonstrated with traditional upright solar cell structures, IMM structures present additional processing challenges. We demonstrate, for the first time, the transfer printing of fully-functional microscale triple-junction (3J) IMM solar cells.

14 SOLAR ENERGY↗
DOE OSTI2012

Development of a High Volume Capable Process to Manufacture High Performance Photovoltaic Cells

The intent of the work is for RFMD and NREL to cooperate in the development of a commercially viable and high volume capable process to manufacture high performance photovoltaic cells, based on inverted metamorphic (IMM) GaAs technology. The successful execution of the agreement will result in the production of a PV cell using technology that is capable of conversion efficiency at par with the market at the time of release (reference 2009: 37-38%), using RFMD's production facilities. The CRADA work has been divided into three phases: (1) a foundation phase where the teams will demonstrate the manufacturing of a basic PV cell at RFMD's production facilities; (2) a technology demonstration phase where the teams will demonstrate the manufacturing of prototype PV cells using IMM technology at RFMD's production facilities, and; (3) a production readiness phase where the teams will demonstrate the capability to manufacture PV cells using IMM technology with high yields, high reliability, high reproducibility and low cost.

14 SOLAR ENERGY↗
DOE OSTI2012

Final Report for PV Incubator Subcontract No. NAT-7-77015-05: October 19, 2007 - July 30, 2009

The Solar America Initiative (SAI) is intended to provide numerous technological routes towards a lower levelized cost of solar-generated electricity (LCOE). MicroLink's planned contribution towards the SAI is to provide a method of lowering the cost of GaAs-based solar cells, which are a major contributor to the cost of concentrator photovoltaic (CPV) modules. MicroLink's unique approach is touse an epitaxial liftoff (ELO) process to completely remove the active solar cell from the substrate while preserving the performance and yield of the cell. The substrate accounts for approximately half the cost of conventional, multijunction GaAs-based solar cells. By using ELO, the substrate can be reused several times for additional solar cell growths, thereby reducing the cost ofmultijunction solar cells by up to 50%. The achievement of high efficiency has significantly increased the acceptance of MicroLink Devices as a future supplier of high-efficiency dual-junction and IMM (inverted metamorphic) triple-junction ELO solar cells. MicroLink entered the SAI program with a 10% efficiency GaAs solar cell (1-sun AM 1.5) and finished the program with an NREL-verified IMMtriple-junction ELO solar cell (1-sun AM 1.5).

14 SOLAR ENERGY↗