Effect of Quantum Confinement on Thermoelectric Properties of 2D and 1D Semiconductor Thin Films

With device dimensions shrinking to nanoscales, quantum effects such as confinement and tunneling become significant in electron transport. In addition, scattering effects such as electron-phonon scattering, electron-impurity scattering also affect carrier transport through small-scale devices. Currently most of the commonly used transport models are particle based with quantum corrections incorporated to include quantum effects while models based on the solution to the Schrödinger wave equation can be computationally intensive. In this regard, the NEGF formalism has been found to be very efficient in coupling quantum and scattering effects. In this paper the NEGF model is used to assess the effect of temperature on device characteristics of 1D and 2D thin film superlattices whose applications include thermoelectric cooling of electronic and optoelectronic systems. The effect of quantum confinement on the electrical transport and its impact on the thermoelectric figure of merit is studied in the two cases. Results show a competing effect between the electrical and thermal conductivity on the overall figure of merit in the two dimensionally confined thin films.