Heteroepitaxial growth of β-Ga2O3 films on SiC via molecular beam epitaxy

beta-Ga2O3 is a promising ultrawide bandgap semiconductor for next generation radio frequency electronics. However, its low thermal conductivity and inherent thermal resistance provide additional challenges in managing the thermal response of beta-Ga2O3 electronics, limiting its power performance. In this paper, we report the heteroepitaxial growth of beta-Ga2O3 films on high thermal conductivity 4H-SiC substrates by molecular beam epitaxy (MBE) at 650 degrees C. Optimized MBE growth conditions were first determined on sapphire substrates and then used to grow beta-Ga2O3 on 4H-SiC. X-ray diffraction measurements showed single phase (201) beta-Ga2O3 on (0001) SiC substrates, which was also confirmed by TEM measurements. These thin films are electrically insulating with a (402) peak rocking curve full-width-at-half-maximum of 694 arc sec and root mean square surface roughness of similar to 2.5 nm. Broad emission bands observed in the luminescence spectra, acquired in the spectral region between near infrared and deep ultraviolet, have been attributed to donor-acceptor pair transitions possibly related to Ga vacancies and its complex with O vacancies. The thermal conductivity of an 81 nm thick Ga2O3 layer on 4H-SiC was determined to be 3.1 +/- 0.5 W/m K, while the measured thermal boundary conductance (TBC) of the Ga2O3/SiC interface is 140 +/- 60 MW/m(2) K. This high TBC value enables the integration of thin beta-Ga2O3 layers with high thermal conductivity substrates to meliorate thermal dissipation and improve device thermal management.