Nanoscale Component\nDiffusion Study of InP/SiC Heterogeneous\nBonding Interface for High-Quality Optoelectronic Device Integration

Indium phosphide (InP) possesses excellent physical and\nelectrical\nproperties, rendering it particularly suitable for optoelectronic\nand high-speed electronic applications and thus making it a potentially\nsignificant material in integrated circuit technology. Integrating\nInP on a substrate with high thermal conductivity, such as silicon\ncarbide (SiC), presents a promising solution to mitigate thermal accumulation\nin InP-based devices. In this study, a hydrophilic bonding process\nwas employed to achieve direct wafer bonding of InP/SiC at room temperature\n(RT), resulting in an average bonding strength of 3.2 MPa and a thermal\nconductivity of 112.60 W m<sup>–1</sup> K<sup>–1</sup> at RT. The interface structure (thinned to 50 nm) was analyzed using\nhigh-resolution transmission electron microscopy (HRTEM), revealing\nclose contact at the InP/SiC bonding interface at RT. Nanoscale component\ndiffusion (1.8 nm) at the interface was found to enhance bonding strength.\nAnnealing treatments at 300 and 600 °C were performed to thoroughly\ninvestigate nanoscale component diffusion and recombination at the\nInP/SiO<sub>2</sub> interface. The results demonstrated component\ndiffusion at RT with a depth of 2.63 nm. At 300 °C annealing,\nrecrystallization of InP/SiO<sub>2</sub> interface components led\nto the formation of indium oxide (In<sub>2</sub>O<sub>3</sub>) with\na crystallization depth of 3.89 nm. At 600 °C, annealing caused\nfurther recrystallization, producing indium phosphate (InPO<sub>4</sub>) with a crystallization depth of 5.50 nm. These results were confirmed\nby X-ray diffraction (XRD) and scanning electron microscopy (SEM)\nanalyses. Nanoscale structural analysis of the InP/SiO<sub>2</sub> interface helps to further understand the mechanisms at heterointerfaces\nand improve the quality of integrated devices. Additionally, simulations\ncalculated the effects of recrystallization products on the optical\nfield mode and transmission loss of the InP waveguide, providing crucial\ndesign guidance for InP optoelectronic integration.