Search

In this work, we report on the realization of vertical (100) β-Ga2O3 FinFET devices for the use in power electronics applications. The experiments are carried out on structures consisting of highly conducting (100) β-Ga2O3 substrates with a doping concentration N D of 3 × 1018 cm−3, and epitaxially grown layers with N D of 5 × 1016 cm−3 for the drift and channel region. The fabricated FinFET devices feature enhancement-mode properties with a threshold voltage of +4.2 V and on/off-current ratio of 105. Moreover, breakdown measurements of these devices reveal an average breakdown strength of 2.7 MV cm−1. Additional device simulation indicates the presence of electric field peaks near the gate edge outside the active device as high as 7 and 5 MV cm−1 in the Al2O3 gate oxide and β-Ga2O3 semiconductor, respectively.

Absrtract In this work, we comprehensively investigate the development of unwanted parasitic particles in the MOVPE chamber while growing μm level films. The density of the parasitic particles is found to be pronounced at film thicknesses starting from >1.5 to 2 μm. These particles seem to induce structural defects such as twin lamellae, thereby harming the electrical properties of the grown film. The origin of the parasitic particle is attributed to the parasitic reactions within the chamber triggered by the promoted gas-phase reactions during the growth process, which can be largely reduced by increasing the total gas flow and decreasing the showerhead distance to the susceptor. A film thickness of up to 4 μm has been achieved after minimizing the density of parasitic particles. Thereby, RT Hall measurements reveal carrier mobilities of 160 cm2V−1s−1 at carrier concentrations of 5.7 × 1016 cm−3.

The influence of chamber pressure and Si-doping on the growth rate, surface morphology and Hall mobility was investigated forβ-Ga2O3thin films homoepitaxially grown by metalorganic vapor phase epitaxy on Mg-dopedβ-Ga2O3(100) substrates with 4° miscut. Transitions from step-bunching to step-flow to 2D island growth modes were achieved by varying the chamber pressure from 10 mbar to 40 mbar and/or by varying the O2/Ga ratio. High-qualityβ-Ga2O3homoepitaxial thin films with a high electron mobility of 153 cm2Vs−1have been obtained at a chamber pressure of 25 mbar and a growth rate of 3.6 nm min−1. The Si-doped films show electron concentrations in the range of 1 × 1017to 2 × 1019cm−3. When increasing the chamber pressure to 40 mbar step-flow growth mode and high charge carrier mobility can only be preserved by adjusting the O2/Ga ratio and increasing the Ar push gas flow. Secondary ion mass spectrometry and Hall measurements for Si and electron concentration, respectively, revealed Si compensation at higher tetraethyl orthosilicate flux.

We report the first demonstration of self-aligned gate (SAG) β-Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) as a path toward eliminating source access resistance for low-loss power applications. The SAG process is implemented with a subtractively defined and etched refractory metal, such as Tungsten, combined with ion-implantation. We report experimental and modeled DC performance of a representative SAG device that achieved a maximum transconductance of 35 mS mm−1 and an on-resistance of ∼30 Ω mm with a 2.5 μm gate length. These results highlight the advantage of implant technology for SAG β-Ga2O3 MOSFETs enabling future power switching and RF devices with low parasitic resistance.