Experimental demonstration of scalability in a cavity-free planar silicon-integrated thermoelectric device

We demonstrate the scalability of cavity-free planar integrated thermoelectric (TE) devices using silicon nanowires (Si-NWs), where miniaturizing the thermoelement by shortening the Si-NWs improves the areal power density. Shortening the Si-NW length decreases the temperature difference between the Si-NW ends and the open-circuit voltage. Meanwhile, the integrated number density of the thermoelement is increased by shortening the Si-NW length, thereby preserving the total electrical resistance. Bileg devices comprising both n- and p-type Si-NWs exhibited superior performance compared to unileg devices comprising only n-type Si-NWs. In unileg devices, the hot and cold electrodes in the adjacent thermoelements are interconnected through metal wiring, which leaks heat, resulting in a lowering of the temperature difference between the Si-NW ends. This study yields structural design guidelines for planar-integrated TE devices using Si-NWs.