Experimental Observation of High Intrinsic Thermal Conductivity of AlN

Abstract

AlN is an ultra-wide bandgap semiconductor which has been developed for applications including power electronics and optoelectronics. Thermal management of these applications is the key for stable device performance and allowing for long lifetimes. AlN, with its potentially high thermal conductivity, can play an important role serving as a dielectric layer, growth substrate, and heat spreader to improve device performance. However, the intrinsic high thermal conductivity of bulk AlN predicted by theoretical calculations has not been experimentally observed because of the difficulty in producing materials with low vacancy and impurity levels, and other associated defect complexes in AlN which can decrease the thermal conductivity. This work reports the growth of thick AlN layers by MOCVD with an air-pocketed AlN layer and the first experimental observation of intrinsic thermal conductivity from 130 K to 480 K that matches density-function-theory calculations for single crystal AlN, producing some of the highest values ever measured. Detailed material characterizations confirm the high quality of these AlN samples with one or two orders of magnitude lower impurity concentrations than seen in commercially available bulk AlN. Measurements of these commercially available bulk AlN substrates from 80 K to 480 K demonstrated a lower thermal conductivity, as expected. A theoretical thermal model is built to interpret the measured temperature dependent thermal conductivity. Our work demonstrates that it is possible to obtain theoretically high values of thermal conductivity in AlN and such films may impact the thermal management and reliability of future electronic and optoelectronics devices.

References in corpus (2)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Calculation of nanowire thermal conductivity using complete phonon dispersion relations

Cited by in corpus (10)

• High Thermal Conductivity in Wafer Scale Cubic Silicon Carbide Crystals
• Three-Sensor 2ω Method with Multi-directional Layout: A General Methodology for Measuring Thermal Conductivity of Solid Materials
• Quasi-Ballistic Thermal Conduction in 6H-SiC
• Machine-Learned Atomic Cluster Expansion Potentials for Fast and Quantum-Accurate Thermal Simulations of Wurtzite AlN
• Excitonic and deep-level emission from N- and Al-polar homoepitaxial AlN grown by molecular beam epitaxy
• High-throughput computational framework for lattice dynamics and thermal transport including high-order anharmonicity: an application to cubic and tetragonal inorganic compounds
• Electro-thermal Co-design of Vertical \b{eta}-Ga2O3 Schottky Diodes with High-permittivity BaTiO3 Field-plate for High-field and Thermal Management
• Impact of AlN buffer thickness on electrical and thermal characteristics of AlGaN/GaN/AlN HEMTs
• Wafer-scale Heterogeneous Integration of Monocrystalline \b{eta}-Ga2O3 Thin Films on SiC for Thermal Management by Ion-Cutting Technique
• Interfacial thermal transport in Si/SiC and SiC/diamond heterostructures: effects of amorphous interlayers and SiC polytypes