GaAs solar cell transfer onto copper substrates via thermocompression bonding for photovoltaic thermoelectric hybridization

Abstract For photovoltaic–thermoelectric energy-conversion systems, thermal management is crucial, in particular at the hybrid interfaces in integrated systems, for achieving the best performances. One of the challenges of this integrated PV–TE system is to ensure compatibility in terms of surface area and power generation between PV and TE modules. This work presents the transfer of a $$0.5\times 0.5$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mo>×</mml:mo> <mml:mn>0.5</mml:mn> </mml:mrow> </mml:math> cm $$^2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>2</mml:mn> </mml:mmultiscripts> </mml:math> GaAs solar cell onto a copper substrate using Au–Au thermocompression bonding, with a WTi barrier layer to prevent Cu diffusion. Structural integrity and limited interdiffusion were confirmed by scanning electron microscopy. The GaAs substrate was removed via selective etching, and issues with etch selectivity were addressed. Comparison of copper substrates showed that electrodeposited copper offers advantages for scalable bonding. These findings offer a promising approach for efficient thermal management and improving efficiency of integrated photovoltaic–thermoelectric systems.