The influence of dielectric layer on the thermal boundary resistance of GaN‐on‐diamond substrate

Abstract

The cooling behavior of GaN‐on‐diamond substrate can be enhanced by reducing the thermal boundary resistance (TBR), which is mainly determined by the nature of interlayer. Although SiN film is considered as the primary candidate of dielectric layer, it is still needed to be optimized. In order to facilitate the understanding of the influence of dielectric layer on the TBR of GaN‐on‐Diamond substrate, aluminum nitride (AlN), and silicon nitride (SiN) film were compared systematically, both of which are 100 nm. The time‐domain thermoreflectance (TDTR) measurements, adhesion evaluation, and microstructural analysis methods were adopted to analyse these two interlayers. The results show the TBR of SiN interlayer is as low as 38.5 ± 2.4 m2K GW−1, comparing with the value of 56.4 ± 5.5 m2K GW−1 for AlN interlayer. The difference of TBR between these two interlayers is elucidated by the diamond nucleation density, and the adhesion between the diamond film and GaN substrate, both of which are affected by the surface charge and chemical groups of the dielectric layer.

DFT-Based Studies on Carbon Adsorption on the wz-GaN Surfaces and the Influence of Point Defects on the Stability of the Diamond–GaN Interfaces

“…The present paper aims to demonstrate that certain reconstruction patterns involving substitutional atoms can improve the energetic stability of the diamond-GaN interfaces, as was observed in the case of diamond-AlN interfaces [26]. Since the proposed reconstruction patterns take place in the GaN substrate, our findings are closely related to GaN-on-diamond experimental approaches where the formation of carbide bonds [27] or a silicon-carbon-nitrogen layer between GaN and diamond [16] was reported.…”

“…In turn, in the experiments on the diamond growth on the GaN covered with a SiN dielectric layer [16], it was concluded that a few-nanometer-thick Si-rich SiN layer could convert to SiC before diamond nucleation, and Si-C bonding during diamond nucleation was beneficial to the strong adhesion of the obtained diamond films.…”

“…However, heterogeneous integration of GaN with diamond leading to the GaN-on-diamond architecture is still challenging. Up to now, three kinds of approaches to fabricate the GaN-on-diamond architecture have been demonstrated: (i) diamond growth on GaN [13][14][15][16], (ii) GaN growth on diamond [17][18][19], and (iii) GaNdiamond bonding technology [20][21][22][23]. In the first two approaches, a nucleation layer is formed at the initial stage of growth, resulting in a large number of defects and grain boundaries at the interface, which have a negative impact on the thermal performance of the GaN-on-diamond device due to the poor thermal conductivity [5].…”

Diamond/GaN HEMTs: Where from and Where to?

“…At the same time the bottleneck of the heat extraction was recognized to be the TBR between GaN and diamond (TBR GaN/diamond ) [72] and most of following research focused on decreasing it, whether by decreasing the dielectric thickness, by using a different dielectric, or by optimizing the diamond nucleation layer [10,[72][73][74][75][76][77][78][79][80][81][82][83][84]. The impact of the thickness of the GaN buffer layer on the R th of the HEMT devices [85][86][87][88][89][90] and the effects of the stress caused by the difference in the CTEs of GaN and diamond [91][92][93][94][95][96] were also evaluated by different research groups.…”

Impact of Die Carrier on Reliability of Power LEDs

“…Free standing diamond has also been used as a sub-mount for lasers [16], [17] as well as a circuit board integrated with water-cooling channels [18]. Gallium nitride (GaN) high electron mobility transistors (HEMTs) also benefit from the integration with diamond films [19]- [23].…”