High-Purity Diamond Integration on β-Ga2O3 via Microwave Plasma CVD for Enhanced Thermal Management
Abstract
The integration of diamond with β-Ga2O3 presents a promising pathway to enhance thermal management in high-power electronic devices, where the inherently low thermal conductivity of β-Ga2O3 can lead to localized self-heating and elevated junction temperatures. In this work, we demonstrate a scalable, low-damage approach for integrating polycrystalline diamond films on (010) β-Ga2O3 substrates via microwave plasma chemical vapor deposition (MPCVD), employing dielectric interlayers and polymer-assisted electrostatic nanodiamond seeding to systematically evaluate the impact of growth conditions on film morphology, grain evolution, phase purity, and optical characteristics. At a growth temperature of 800, progressive grain coarsening is observed with extended deposition, with the lateral grain size increasing from 37.6 nm (53 nm thickness) to 192.5 nm for an 886 nm-thick film. This microstructural evolution is accompanied by narrowing of the diamond Raman peak and a monotonic increase in the sp3 phase fraction from 95.9\% to as high as 98.9\%, indicating continued suppression of non-diamond carbon with prolonged growth. Comparison of SiO2 and SiNx interlayers under identical growth conditions shows only marginal differences in grain size and phase purity, indicating limited interlayer influence once a high nucleation density is established. Importantly, diamond films exhibiting greater than 96\% sp3 phase content were achieved at substrate temperatures as low as 480, highlighting the viability of diamond-on-Ga2O3 integration under reduced thermal budgets. These findings establish a robust and scalable platform for integrating diamond on β-Ga2O3, supporting the development of next-generation power and RF devices with improved thermal management.