Thermal Analysis of AlGaN/GaN HEMTs Using Angular Fourier-Series Expansion

Abstract

Thermal analysis of planar and near-square semiconductor device chips employing angular Fourier-series (AFS) expansion is presented for the first time. The determination of the device peak temperature using AFS requires only a single two-dimensional computation, while full three-dimensional temperature distribution can be obtained, if desired, by successively adding higher-order Fourier terms, each of which requires a separate 2D computation. The AFS method is used to compare the heat spreading characteristics of AIGaN/GaN high-electron-mobility transistors (HEMTs) fabricated on silicon, silicon carbide, and synthetic diamond. We show that AIGaN/GaN HEMTs built using GaN/diamond technology can offer better than half the thermal resistance of GaN/SiC HEMTs under worst-case cooling conditions. Furthermore, we show that, if left unmanaged, an inherent and non-negligible thermal boundary resistance due to the integration of semiconductor epilayers with non-native substrates will dampen the benefits of highly conductive substrates such as SiC and diamond.

Influence of Prestress Fields on the Phonon Thermal Conductivity of GaN Nanostructures

“…Adopting the manner utilized by Morse to solve the displacements in Eq. (2) for nanowires, the relations between the frequency and the wave vector in the compressional modes is modified by (C" + < 7°u )q2 i + (Cn + a°22)h2 = pnewa>2 -(Cl3 -a%)q2 (C66 + < 7jj)< 5<2 + (2C65 -C 44 + a22)h2 = pnewco2 -(C44 + a°33)q2 (10) According to the definition J = -kVT, the phonon thermal con ductivity can be expressed as [38,40] x V (** -1)…”

“…GaN, as a group-II-V V wide-band-gap semi conductor, has been extensively explored and receiving a growing research attention because of its enhanced physical properties and stability at high temperatures [3][4][5]. Nanostructured GaN is a promising candidate for potential nanoscale device applications in optoelectronics [6,7], high-power electronics [8], ultrapower switches [9,10], and biochemical-sensing [11,12], Thermal man agement is of critical importance in these devices applications, particularly as continuous reduction of the electronic device fea ture size into nanometers scale. The performance and reliability of semiconductor-based nano-electronic devices depend on the heat dissipation in the active regions.…”