Toward Hot Carrier Extraction in Intervalley Photovoltaic Devices

InGaAs heterostructures have demonstrated the means to maintain high energy '"hot"carrier behavior under practical operating conditions via transfer to upper valleys of the band structure, potentially decreasing thermalization losses in solar cells if a suitable extraction mechanism is developed. A set of four InGaAs heterostructures with altered n+ top layers enable comparative analysis of the current density-voltage characterization and the relationship to the band and valley alignments. This reveals that the barriers to extraction are introduced by the challenges of real space transfer between upper valleys of different materials rather than an energy level mismatch at the top heterojunction.