Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

M. T. Alam, M.S. Bresnehan, J. A. Robinson and M. A. Haque

 

Summary: Large area CVD grown hexagonal boron nitride films may not outperform their exfoliated counterparts but can carry heat 100 times better than conventional dielectrics. That is quite impressive considering their compatibility towards sustainable 2D device fabrication.

 

Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 10 W m-1K-1, is lower than the bulk basal plane value (390 W m-1K-1) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

(a)    Infrared thermograph of a 10 nm thick h-BN film supported on MEMS heater (b) extraction of thermal conductivity from a steady state energy balance model

 

We also performed transient experiments that measure thermal diffusivity (and hence thermal conductivity if specific heat and density are known). The results match very well with the steady state experiments.

 

Combination of (a) spatial and (b) temporal temperature profile allows measurement of the thermal diffusivity.