High power efficiency nitrides thermoelectric device

III-Nitrides, especially InGaN, are promising for high-efficiency thermoelectric (TE) components operating at high temperatures (HTs), playing a critical role in the recovery of waste heat for sustainable energy development. However, the performance of InGaN TE materials is limited by the high thermal conductivity (k) and the conflict coupling between the power factor (PF) and the k. Here, the previously unstudied two-dimensional InGaN/GaN SL structured TE device with a high In composition of 31% was developed and demonstrated to improve the TE figure of merit (ZT, Z = PF/k) by reducing the k value without deteriorating the PF. The Seebeck coefficient (S) exhibited a value of -365 mu V/K due to the increased density of electron states near the Fermi level by the low dimensional construction. Simultaneously, a relatively low k was obtained as 7.7 W/m.K, benefitting from the alloying and SL interface scattering effect of high energy phonons. Moreover, enhancement of the Umklapp process by the space confinement effect further lowers the k. Accordingly, a record ZT value of 0.089 at 300 K was achieved, which was better than previously reported values for GaN-based TE film materials. This work provides a new material system for improving the performance of nitride TE materials at HTs and extends the fields of application in electricity harvesting from waste heat.

Automated summary

A new two-dimensional InGaN/GaN SL structured TE device was developed, which successfully improved the TE performance parameter by reducing the thermal conductivity without deteriorating the power factor. This research provides a new material system for improving the performance of nitride TE materials at high temperatures and extends the application fields of electricity harvesting from waste heat.