Programming emissivity on fully integrated VO2 windows

The programmability of emissivity states in a monolithically integrated micro window based on vanadium dioxide (VO2) thin film is demonstrated. The 400 window features a VO2 thin film with integrated electrodes for actuation and sensing. The phase transition was induced by resistive heating, while the electrical resistivity and optical transmittance (for near IR wavelength of 1550 nm) of the VO2 thin film were monitored simultaneously. Abrupt drops in electrical resistance and optical transmittance confirmed the quality of the VO2 thin film. Electronic pulses were used to program emissivity states in the VO2 window. The emissivity programmed state was shown for a specific DC current over imposed with the programming pulse; but any emissivity state that belongs to the minor hysteretic curves can be obtained by choosing different electronic inputs. The fully monolithically integrated device presented here can be used for IR cloaking applications, where different emissivity values can be