Role of polarization electric field on thermal conductivity of GaN/In0.9Ga0.1N/GaN superlattices

Abstract

Enhancement in thermoelectric efficiency of GaN/In0.9Ga0.1N/GaN superlattice (SL) needs higher electrical conductivity (σ) and Seebeck coefficient (S); but lower thermal conductivity (k). Both S and σ are improved due to the presence of polarization electric field (PEF) of this SL. In this work, the role of PEF on k of SL has been investigated and found that cross-plane and in-plane k are reduced due to PEF upto a certain temperature. Both cross-plane and in-plane thermal conductivities in the presence of PEF show cross over temperature termed as transition temperature(Tc ). It is noted the Tc for cross-plane and in-plane thermal conductivity of GaN/In0.9Ga0.1N superlattice (SL) are 510K and 530K, respectively which depends on In contents. Thus, the preferred value of S, σ and k of GaN/In0.9Ga0.1N SL can be achieved as per requirement by changing In content; making it suitable for TE module for maximum power production at room temperature and above.