Thermoelectric properties and thermoelectric devices of free-standing GaN and epitaxial GaN layer

We studied the thermoelectric properties of free-standing GaN (fr-GaN) and epitaxial GaN layer (epi-GaN), and furthermore, we have fabricated thermoelectric devices using these materials. For fr-GaN, the maximum power factor was 7.7 × 10− 4 W/m K2 at 373 K, and for epi-GaN layer, the maximum power factor was 9.4 × 10− 4 W/m K2 at 373 K. The devices fabricated are (a) fr-GaN and chromel of 4 pairs, and (b) epi-GaN and chromel of 3 pairs. The maximum output power and the open output voltage were (a) 3.35 × 10− 6 W and 2.76 × 10− 2 V at ΔT = 153 K, and (b) 1.21 × 10− 7 W and 1.71 × 10− 2 V at ΔT = 153 K, respectively.