Properties for Thermally Conductive Interfaces with Wide Band Gap Materials

Abstract

The goal of this study is to determine how bulk vibrational properties and interfacial structure affect thermal transport at interfaces in wide band gap semiconductor systems. Time-domain thermoreflectance measurements of thermal conductance G are reported for interfaces between nitride metals and group IV (diamond, SiC, Si, and Ge) and group III–V (AlN, GaN, and cubic BN) materials. Group IV and group III–V semiconductors have systematic differences in vibrational properties. Similarly, HfN and TiN are also vibrationally distinct from each other. Therefore, comparing G of interfaces formed from these materials provides a systematic test of how vibrational similarity between two materials affects interfacial transport. For HfN interfaces, we observe conductances between 140 and 300 MW m –2 K –1 , whereas conductances between 200 and 800 MW m –2 K –1 are observed for TiN interfaces. TiN forms exceptionally conductive interfaces with GaN, AlN, and diamond, that is, G > 400 MW m –2 K –1 . Surprisingly, interfaces formed between vibrationally similar and dissimilar materials are similarly conductive. Thus, vibrational similarity between two materials is not a necessary requirement for high G . Instead, the time-domain thermoreflectance experiment (TDTR) data, an analysis of bulk vibrational properties, and transmission electron microscopy (TEM) suggest that G depends on two other material properties, namely, the bulk phonon properties of the vibrationally softer of the two materials and the interfacial structure. To determine how G depends on interfacial structure, TDTR and TEM measurements were conducted on a series of TiN/AlN samples prepared in different ways. Interfacial disorder at a TiN/AlN interface adds a thermal resistance equivalent to ∼1 nm of amorphous material. Our findings improve fundamental understanding of what material properties are most important for thermally conductive interfaces. They also provide benchmarks for the thermal conductance of interfaces with wide band gap semiconductors.

High thermal conductivity in wafer-scale cubic silicon carbide crystals

“…The stacking faults density observed on the growth face is about 1000 cm −1 according to cross-sectional TEM study. The thermal conductivity of thermally thick 3C-SiC films grown on (100) Si purchased from MTI is only 90 W m −1 K −1 , which is significantly lower than that of our samples 42 .…”

Interfacial Optimization for AlN/Diamond Heterostructures via Machine Learning Potential Molecular Dynamics Investigation of the Mechanical Properties

“…Its impact extends to material stability, band structure, and ferroelectricity, thus catalyzing advancements in the field of strain engineering. Although the AlN/diamond heterostructures have been extensively studied in the fabrication process as well as the thermal properties in the previous research efforts, ,− the mechanical properties of the heterogeneous interfaces between AlN and diamond remain unexplored because it is really challenging for the direct observation and description of the interfacial failure mechanisms of the heterostructures through the experimental methods. Molecular dynamics (MD) simulations can provide a methodology for in-depth study of interfacial interactions, and tensile strain simulations can furthermore reveal the mechanisms of structural evolution under various influencing factors, including crystal structure, thermal transport, and tensile and compressive stresses.…”

Intramolecularly Stabilized o-Carboranyl Aluminum Complexes: Synthesis, Characterization, and X-ray Structural Studies

“…Various organoaluminum compounds with C,N-chelating ligands have been prepared for the purpose of bonding to aluminum atoms via Al-C covalent bonds and Al-N dative bonds [2][3][4][5][6][7][8][9][10][11][12]. Recently, interest in aluminum nitride (AlN) [13], a form in which aluminum and nitrogen are combined, has been on the rise due to AlN being one of the few materials with both a wide direct bandgap and large thermal conductivity [14][15][16][17][18][19][20]. Group 13 metal nitrides are commonly used in optoelectronics [21][22][23][24][25][26], as well as in high-power and high-frequency electronics [27][28][29][30][31], owing to their small atomic mass, strong interatomic bonds, and simple crystal structure [32].…”