Thermal boundary conductance across metal-gallium nitride interfaces from 80 to 450 K

Abstract

Thermal boundary conductance is of critical importance to gallium nitride (GaN)-based device performance. While the GaN-substrate interface has been well studied, insufficient attention has been paid to the metal contacts in the device. In this work, we measure the thermal boundary conductance across interfaces of Au, Al, and Au-Ti contact layers and GaN. We show that in these basic systems, metal-GaN interfaces can impose a thermal resistance similar to that of GaN-substrate interfaces. We also show that these thermal resistances decrease with increasing operating temperature and can be greatly affected by inclusion of a thin adhesion layers.

Size dictated thermal conductivity of GaN

“…Thermal boundary conductance ranges in magnitude from 118 to 278 MW/m 2 K in line with the previous measurements 41 independent of either type or degree of doping. Thermal conductivity, in contrast, varies with dopant type and concentration.…”

Measurement Techniques for Thermal Conductivity and Interfacial Thermal Conductance of Bulk and Thin Film Materials

“…As shown in Figure 19, the TDTR signal is dominantly determined by the interfacial thermal conductance when delay time is longer than 2 ns. TDTR technique is therefore implemented extensively to study the thermal transport mechanisms across interfaces, including the effect of surface chemistry on interfacial thermal conductance across functionalized liquid-solid boundary [95,117,118] and solid-solid interfaces [119], interfacial thermal conductance between metals and dielectrics, [120][121][122][123][124] and interface between low dimensional materials and bulk substrates [125][126][127] Let's consider bulk materials first to introduce the physical picture we based on to determine heat capacity and thermal conductivity simultaneously. Under periodic laser heating, the penetration depth is defined as a characteristic length which describes the depth of temperature gradient penetrates into the sample can be written as , = √2 / 0 where 0 is the modulation frequency, is volumetric heat capacity and the index of directions corresponds to in-plane ( = ) and cross-plane ( = ) respectively.…”

The Impact of Nongray Thermal Transport on the Temperature of AlGaN/GaN HFETs

“…Thermal boundary resistance of 3.3 × 10 −8 m 2 K/W was applied at the SiC and GaN interface [24]. The thermal effects caused by the metallization layers and the thermal boundary resistance between metal/AlGaN layers [25] are ignored with the assumption that the majority of the heat is dissipated from the hotspot is carried away through substrate and the CuW package, which is typical for most high power GaN RF-devices.…”