Radiative Cooling of a Silicon Nitride Nanomechanical Resonator

Radiative cooling allows for the temperature of an object to diminish below ambient temperature by coupling it with the coldness of outer space via thermal radiation. Creating local thermal gradients on-chip with this phenomenon could potentially enable microscale energy conversion devices running on ambient heat. Here, we demonstrate localized radiative cooling of an on-chip silicon nitride membrane by up to 6.4 K at night, and 5.4 K during the day, under direct sunlight. This is in agreement with our theoretical model, which predicts a temperature drop of 5 K - 9 K for our experimental parameters, and a maximal drop of 15 K in ideal field of view and atmospheric conditions.