Ultra-Wide Band Gap Ga₂O₃-on-SiC MOSFETs

Abstract

Ultra-wide band gap semiconductor devices based on β-phase gallium oxide (Ga2O3) offer the potential to achieve higher switching performance and efficiency and lower manufacturing cost than that of today’s wide band gap power electronics. However, the most critical challenge to the commercialization of Ga2O3 electronics is overheating, which impacts the device performance and reliability. We fabricated a Ga2O3/4H–SiC composite wafer using a fusion-bonding method. A low-temperature (≤600 °C) epitaxy and device processing scheme was developed to fabricate MOSFETs on the composite wafer. The low-temperature-grown epitaxial Ga2O3 devices deliver high thermal performance (56% reduction in channel temperature) and a power figure of merit of (∼300 MW/cm2), which is the highest among heterogeneously integrated Ga2O3 devices reported to date. Simulations calibrated based on thermal characterization results of the Ga2O3-on-SiC MOSFET reveal that a Ga2O3/diamond composite wafer with a reduced Ga2O3 thickness (∼1 μm) and a thinner bonding interlayer (<10 nm) can reduce the device thermal impedance to a level lower than that of today’s GaN-on-SiC power switches.

Ultrafast Multifunctional Photodetector Based on the NiAl2O4/4H-SiC Heterojunction

“…Thus, the work function (Φ) of the NAO film is Φ = 21.22 − (17.97 − 0) = 3.25 (eV). 46,47 The distance between the highest occupied state (HOS) and the Fermi energy level is 1.23 eV, which is consistent with the XPS results. As a result, a typical p−n junction with a large built-in field can be formed at the interface of the NAO/4H-SiC junction.…”

Temperature-dependent Raman-active phonon modes and electron−phonon coupling in β-Ga2O3 microwire

“…atoms in crystal will be enhanced, which will weaken the interaction between atoms and that between unit cells, leading to a decrease in the vibration frequency and redshifts of Raman peak position. 28) However, the experimental results show that the five peaks of the B g (1) , A g (2) , A g (3) , A g (4) and A g (6) modes first exhibit blueshifts and then redshifts, a phenomenon different to that of the corresponding Raman shifts of bulk single crystal, and their first-order temperature coefficients are negative. This is possibly due to the fact that the effect of temperature on interatomic spacing along the growth direction is different to that perpendicular to the growth direction.…”

“…These results reveal that the Ga I (O I ) 2 groups, Ga I (O II ) 2 groups and Ga II 3+ ions microwire have higher symmetry, while there are few differences in the properties between the stretching and bending of Ga I O 4 -tetrahedra in microwire and in bulk single crystal. As the temperature increases, the B g (1) , A g (2) , A g (3) , A g (4) and A g (6) peaks first exhibit blueshifts and then redshifts, a phenomenon different to that for bulk single crystal, while the other ten Raman peaks are redshifted. For PL spectroscopy, the luminescence at RT is bright in the UV band and weak in the blue band, while it almost disappears in the green and red bands, indicating that the β-Ga 2 O 3 microwire has a high crystalline quality and there is no more defect level or impurity level in the band gap.…”

“…This ultra-wide bandgap semiconductor has promising applications in the new generation of power devices and solar-blind UV photodetectors. [1][2][3] β-Ga 2 O 3 bulk single crystal, thin film and other materials made of β-Ga 2 O 3 have been extensively studied. Recently, high-quality β-Ga 2 O 3 microwire has been grown by CVD, 4,5) optical vapor supersaturated precipitation 6) and exfoliation.…”

“…In the low frequency (<250 cm −1 ), the FWHM of the Raman peaks of the microwire are much narrower than those of bulk single crystal except the A g (3) peak, and even the FWHM of the B g (1) peak of the microwire is narrower than 50% of that of bulk single crystal. The A g (1) , B g (2) and A g (2) modes represent the symmetry of the translations of Ga I (O) 4 -tetrahedra chains along the b-axis, a-axis and the axis perpendicular to the b and c axes in Fig. 1(c), respectively.…”