Reduced thermal boundary conductance in GaN-based electronic devices introduced by metal bonding layer

Abstract

Achieving high interface thermal conductance is one of the biggest challenges in the nanoscale heat transport of GaN-based devices such as light emitting diodes (LEDs), and high electron mobility transistors (HEMTs). In this work, we experimentally measured thermal boundary conductance (TBC) at interfaces between GaN and the substrates with AuSn alloy as a commonly-used adhesive layer by time-domain thermoreflectance (TDTR). We find that the TBCs of GaN/Ti/AuSn/Ti/Si, GaN/ Ti/AuSn/Ti/SiC, and GaN/Ti/AuSn/Ti/diamond, are 16.5, 14.8, and 13.2 MW•m -2 •K -1 at room temperature, respectively. Our measured results show that the TBC of GaN/Ti/AuSn/Ti/SiC interface is inferior to the TBC of pristine GaN/SiC interface, due to the large mismatch of phonon modes between AuSn/Ti and substrates, shown as the difference of Debye temperature of two materials. Overall, we measured the TBC at interface between GaN and thermal conductive substrates, and provided a guideline for designing the interface between GaN and substrate at HEMT from a thermal management point of view.

A Critical Review of Thermal Boundary Conductance across Wide and Ultrawide Bandgap Semiconductor Interfaces

“…61,82,104−107 These advanced technologies have successfully integrated GaN and G a 2 O 3 w i t h s i n g l e c r y s t a l d i amond. 52,66,[82][83][84][85][86][87][88][89][90][91][92]99,104,105,108,109 Figure 5 shows some examples of the interfaces formed by advanced growth or bonding technologies. It is seen that all have close atomic contact without voids or gaps.…”

“…The methods together with their advantages and disadvantages are summarized in Table . They include molecular beam epitaxy (MBE), − atomic layer deposition (ALD), physical vapor deposition (PVD) chemical vapor deposition (CVD), ,,,− metal–organic chemical vapor deposition (MOCVD), ,, plasma bonding, and very recently developed nanoscale graphoepitaxy, hydrophobic bonding, hydrophilic bonding, , and room-temperature (RT) surface-activated bonding (SAB). ,,− These advanced technologies have successfully integrated GaN and Ga 2 O 3 with single crystal diamond. ,,− ,− ,,,,, Figure shows some examples of the interfaces formed by advanced growth or bonding technologies. It is seen that all have close atomic contact without voids or gaps.…”

“…Much recently, Yang et al 83 estimated the overall heat dissipation performance of GaN/Si interface with commonly used solders like AuSn as bonding layers, instead of AlN, grown by PVD. The total TBC was shown to be 16.5 MW m −2 K −1 , substantially lower than others' data.…”