Increased thermal conductivity of free‐standing low‐dislocation‐density GaN films

Proposed high‐power electronic and optoelectronic applications of GaN materials rely heavily on the effectiveness of heat removal from the devices. Here we report the results of our measurements of thermal conductivity in the thick free‐standing GaN films prepared by hydride vapor phase epitaxy. The fabrication method allows one to grow the low‐dislocation density films without the use of non‐native substrates. Our experimental data show that the room tempera‐ ture thermal conductivity in free‐standing GaN films can be as high at 225 W/mK, which is a factor of 1.8 increase compared to a reference GaN film grown on sapphire substrate. The modeling, performed for the given sample parameters, indicates that the low‐temperature thermal conductivity can reach a record value of 7460 W/mK. The presented results are important for the thermal management optimization of GaN‐based devices. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)