Interfacial electric field and cross-plane thermal conductivity of GaN/InxGa1-xN superlattices (x = 0.1 and 0.3)

Abstract

Superior thermoelectric property requires high electrical conductivity ( $$\sigma$$ ), Seebeck coefficient (S) but low thermal conductivity (k). GaN/InxGa1-xN/GaN superlattice (SL) has a strong interfacial polarization electric (IPE) field ~ 1 MV/cm at hetero-interfaces. Experiments reported that IPE field enhances S and $$\sigma$$ of the SL. In this paper, IPE field on thermal boundary resistance (TBR) and cross-plane thermal conductivity (kcp) of the SL is explored for indium contents x = 0.1 and 0.3 theoretically. IPE field revises phonon velocity causing enhanced boundary/interface scattering. Our result shows that TBR is enhanced (2.10–5. 30) ✕ 10–9 m2 KW−1 due to unequal changes in specific heat and phonon velocity on both sides of interface leading to decreased phonon transmission and acoustic properties of material become more dissimilar under IPE field. This reduced kcp. For GaN (10 nm)/InxGa1-xN (5 nm) SL, room-temperature (RT) kcp in the presence (absence) of IPE field is 4.652 (5.720) and 4.282 (5.221) Wm−1 K−1, respectively, for x = 0.1 and 0.3 proving more than 20% reduction. This work demonstrates that desired value of k can be achieved by tailoring interfacial polarization field of SL for optimum power production at RT and above.