Thermopower profiling across a silicon p-n junction through the 2ω signal measurement of AC current-heated tip-sample nano-contact

Thermopower profiling with nanometer resolution has important applications in the development of nano-structured high ZT thermoelectric materials and in dopant density profiling of nano-electronic devices. We suggested a new AC type thermopower measurement technique and demonstrated it with a simple experimental setup. Thermopower distribution across a silicon p-n junction was measured point-by-point at every 10 nm free from the noises due to built-in potential andphoto-ionization effect and compared with theoretical result. Although this new AC type thermopower measurement technique could not follow the sharp variation of the theoretical thermopower near the p-n junction, it could identify a smooth peak of thermopower distribution in the depletion layer of the p-n junction.