Tunable near-field radiative transfer by III-V group compound semiconductors

Near-field radiative transfer (NFRT) refers to the energy transfer mechanism which takes place between media separated by distances comparable to or much smaller than the dominant wavelength of emission. NFRT is due to the contribution of evanescent waves and coherent nature of the energy transfer within nano-gaps, and can exceed Planck's blackbody limit. As researchers further investigate this phenomenon and start fabrication of custom-made platforms, advances in utilization of NFRT in energy harvesting applications move forward day by day. In designing and manufacturing such harvesting devices, chemical and physical properties of surfaces and wafers are important for development of effective solutions. In this work, we compare several III-V group compound semiconductor wafers (mainly GaAs, InSb, and InP) from fabrication point of view, in order to explore their possible use in future devices. The results presented here show that the type of dopant, wafer temperature, and gap size are very important factors as they affect the NFRT rates. GaAs, InSb, and InP wafers significantly enhance the near-field fluxes beyond the blackbody rates, and n-type InSb yields to the highest enhancement. For GaAs, p-type yielded a higher radiative flux compared to n-type GaAs, as oppose to n-type InSb outperforming its p-type and undoped counterparts. Furthermore, the possible use of n-InSb as the TPV cell at 550 K is discussed for effective energy harvesting. These findings can be useful for determination of the proper material type for emitting and non-emitting NFRT-based energy harvesting devices.