Thermoelectric properties of GaN with carrier concentration modulation: an experimental and theoretical investigation

The present work investigates the less explored thermoelectric properties of n-type GaN semiconductors by combined both experimental and computational tools. Seebeck coefficients epitaxial thin films were experimentally measured in wide temperature range from 77 K to 650 steps ~10 covering low high-temperature regimes as a function carrier concentration 2 x1016, x 1017, 4 1017 8 cm-3. coefficient at room was found be highest, -374 microV/K, lowest 1016 cm-3 decreases magnitude monotonically (-327.6 -295 -246 microV/K for cm-3, respectively) samples increases. remains negative entire under study indicate that electrons are dominant carriers. To understand temperature-dependent behavior, we have also carried out electronic structure, transport calculations using Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, semiclassical Boltzmann theory implemented WIEN2k BoltzTraP code, respectively. observed concentrations used calculations. estimated results obtained constant relaxation time approximations provide very good agreement between theoretical data 260 625 K.