Thermal Resistance of GaN / AlN Graded Interfaces

Abstract

Compositionally graded interfaces in power electronic devices eliminate dislocations, but they can also decrease thermal conduction, leading to overheating. We quantify the thermal resistances of GaN/AlN graded interfaces of varying thickness using ab initio Green's functions, and compare them with the abrupt interface case. A non-trivial power dependence of the thermal resistance versus interface thickness emerges from the interplay of alloy and mismatch scattering mechanisms. We show that the overall behavior of such graded interfaces is very similar to that of a thin-film of an effective alloy in the length scales relevant to real interfaces.

Thermal conductance across harmonic-matched epitaxial Al-sapphire heterointerfaces

“…7,13,55,56 A unified understanding of interfacial thermal transport across metal-nonmetal interfaces does not exist possibly due to the lack of systematic benchmark studies of well-controlled interface growth, simultaneous structural and thermal characterizations, and corresponding comparison with thermal modellings because very few computational methods can take interface non-idealities into consideration. 44,57,58 In this work, we fill the gap by epitaxially growing (111) Al on (0001) ultraclean sapphire substrates by Molecular Beam Epitaxy (MBE). The Al-sapphire system is particularly suitable for benchmarking because of the atomically smooth surfaces, easy cleaning by baking at high temperatures in ultrahigh vacuum (UHV) conditions, no surface oxidation during baking, and no reaction with Al during growth.…”

“…Furthermore, Ye et al 34 deposited metals on Si substrates first, and then annealed the samples to induce reaction growth of metal silicide, which is difficult to control the sharpness and atomic diffusion near the interfaces. However, very few computational methods can take interface non-idealities into consideration 45,46 .…”

Особенности теплопереноса в гетероструктурах Al-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N/GaN на сапфире

“…В гетероструктурах Al x Ga 1−x N/GaN граничные тепловые сопротивления между слоями структуры создают значительные ограничения для теплопереноса [6,7]. Но граничное тепловое сопротивление между слоями Al x Ga 1−x N с градиентным изменением массовой доли x много меньше сопротивления, вызываемого рассеянием на дефектах в сплаве [8]. Это позволяет рассматривать использование подобной структуры буферных слоев в качестве перспективной для оптимизации теплового поведения ТВПЭ.…”

Cross-plane thermal conductivity of GaN/AlN superlattices

“…A decrease of the bulk thermal conductivity of III-nitrides due to impurity doping [26][27][28][29] was also found, while an enhanced conductivity is reported for isotopically enriched GaN 30 . For AlN/GaN stacks, significant changes in the phonon properties due to interface effects [31][32][33][34] and strain 35 were reported, while for compositionally graded interfaces it was found that alloy scattering is dominant over mismatch scattering 36 of phonons.…”