A new path towards ultra-high efficient laser power converters: Silicon carbide-based multijunction devices

Abstract

Current high power laser transmission technology faces two major limitations to improve the efficiency of the photovoltaic receivers: the intrinsic entropic losses associated to low bandgap materials (such as GaAs) and the series resistance losses that degrade the device performance at high power densities. The use of high bandgap materials and new architectures for laser power converters (LPC) have been pointed out as alternatives to overcome these limitations. In this work, three silicon carbide polytypes (3C, 4H and 6H) are proposed as base materials for the standard horizontal laser power converter (hLPC) architecture and the Vertical Epitaxial Hetero-Structure Architecture (VEHSA). 3C SiC based hLPCs outperform the power converters based on the other two polytypes, achieving a maximum efficiency of 84.6% at 100Wcm−2, but suffer from series resistance losses, that deteriorate their efficiency, at higher laser power densities. This issue is solved with 3C SiC 4 cells VEHSAs that demonstrated increasing efficiency with the input power, reaching a maximum of 87.4% at 3000Wcm−2. The VEHSA reduced number of cells minimize the risks of efficiency losses due to current mismatch between cells. These results support the feasibility of a new generation of LPCs capable of efficiently convert ultra-high laser power densities.