Heterojunction for Multi-Junction Solar Cells

Technology Marketing SummarySandia National Laboratories has created a semiconductor p-n heterojunction for use in forming a photodetector that has applications for use in a multi-junction solar cell and detecting light at an energy greater than 0.95-1.2 eV. DescriptionThis semiconductor is made up of a layer of indium gallium arsenide nitride (InGaAsN) with n-type doping that is epitaxially grown in contact with a layer of gallium arsenide (GaAs) with p-type doping.  The InGaAsN/ GaAs semiconductor p-n heterojunction of the present invention can be use in combination with semiconductor p-n homojunctions of conventional design to form an efficient multi-junction solar cell. Benefits

• Forms an efficient 0.95-1.2 eV bandgap pohotodetector for use in a multifunction solar cell
• Contacting layers of p-type GaAs overcomes the limitation of a low electron diffusion that occurs in homojunctions or heterojunctions formed in part from p-type InGaAsN
• The n-type InGaAsN and p-type GaAs provide a substanial increase in open-circuit voltage and short-circuit current as compared to homojunctions and heterojunctions formed in part from p-type InGaAsN
• In space applications, an increased solar cell efficiency is advantageous for increasing the available electrical power or reducing satellite mass and launch cost. 

Applications and Industries

• Generation of electricity for space photovoltaic applications
• Terrestrial high-concentration photovoltaic applications

Patents and Patent Applications

ID Number	Title and Abstract	Primary Lab	Date
Patent 6,252,287	InGaAsN/GaAs heterojunction for multi-junction solar cells An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 0<x.ltoreq.0.2 and 0<y.ltoreq.0.04 and a p-type GaAs layer, with the InGaAsN and GaAs layers being lattice-matched to the substrate. The InGaAsN/GaAs p-n heterojunction can be epitaxially grown by either molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). The InGaAsN/GaAs p-n heterojunction provides a high open-circuit voltage of up to 0.62 volts and an internal quantum efficiency of >70%.	Sandia National Laboratories	06/26/2001 Issued

Technology Status

Technology ID	Development Stage	Availability	Published	Last Updated
US Patent# 6,252,287	Prototype - Sandia estimates this technology at approximately TRL 5. Key elements of this technology have been demonstrated in relevant environments.	Available - Various licensing and partnering options are available. Please contact the Intellectual Property department to discuss.	08/25/2011	03/12/2013