FEM thermal and stress analysis of bonded GaN-on-diamond substrate

Abstract

A three-dimensional thermal and stress analysis of bonded GaN on diamond substrate is investigated using finite element method. The transition layer thickness, thermal conductivity of transition layer, diamond substrate thickness and the area ratio of diamond and GaN are considered and treated appropriately in the numerical simulation. The maximum channel temperature of GaN is set as a constant value and its corresponding heat power densities under different conditions are calculated to evaluate the influences that the diamond substrate and transition layer have on GaN. The results indicate the existence of transition layer will result in a decrease in the heat power density and the thickness and area of diamond substrate have certain impact on the magnitude of channel temperature and stress distribution. Channel temperature reduces with increasing diamond thickness but with a decreasing trend. The stress is reduced by increasing diamond thickness and the area ratio of diamond and GaN. The study of mechanical and thermal properties of bonded GaN on diamond substrate is useful for optimal designs of efficient heat spreader for GaN HEMT.

Diamond/GaN HEMTs: Where from and Where to?

“…A more detailed description and discussion of the main findings is included in Section 4.1. The mechanical and thermo-mechanical integrity of the diamond/GaN interface, which impacts profoundly the reliability of the devices, was also addressed [97][98][99]. As a general finding, Liu et al concluded that the GaN/diamond interface has a high mechanical stability, showing the potential of this material system for the fabrication of reliable devices [97].…”

Thermal Analysis of AlGaN/GaN HEMTs Considering Anisotropic And Inhomogeneous Thermal Conductivity

“…An isothermal surface of 300 K is applied at the bottom of the substrate and other external surfaces are assumed to convect naturally. Here, the natural air convection coefficient and ambient temperature are set as 20 W/(m 2 K) [19,20] and 300 K. For accuracy, the temperaturedependent thermal conductivity of the substrate layer is considered. The thermal parameters of each layer used in the simulation are summarized in Table 2.…”