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We demonstrate an Nb 2 O 5 / β - Ga 2 O 3 metal–insulator–semiconductor (MIS) hetero-junction diode with Nb 2 O 5 as the high-k dielectric insulator for more efficient electric field management resulting in enhanced breakdown characteristics compared to a β - Ga 2 O 3 Schottky barrier diode. Nb 2 O 5 dielectric films were grown using atomic layer deposition and exhibited a high dielectric constant of 50. The high dielectric constant resulted in a 5 × lower electric field at the metal/dielectric interface in the MIS diode compared to the metal/ β - Ga 2 O 3 interface in the Schottky barrier diode. With good electron conduction in forward bias enabled by the negative conduction band offset of Nb 2 O 5 with respect to β - Ga 2 O 3 , the MIS design led to a 3 × improvement in the reverse blocking voltage with a slight trade-off in the specific on-resistance. Overall, a 3.3 × increase in the power figure of merit was observed (3.25 MW / cm 2 for the Schottky diode and 10.8 MW / cm 2 for the MIS diode). A detailed analysis of the energy band line-up and the forward and reverse current transport mechanisms are also presented using analytical modeling and 2D technology computer-aided design simulations. [ABSTRACT FROM AUTHOR]

Ternary dielectrics with varying composition formed by alloying two binary oxides can enable tunable optical and electrical properties for advanced technological applications. Atomic layer deposition (ALD) gives precise control over ternary dielectric composition through the ability to finely tune the precursor pulsing ratio. This work presents ALD development of Si-rich SixTi1−xO2 dielectrics with varying composition (x), along with spectroscopic and electrical characterization of their properties. Stoichiometry of the SixTi1−xO2 films was determined using X-ray photoelectron spectroscopy. Their composition-dependent refractive index, energy bandgap, and reflectance show promise for diverse optical applications ranging from anti-reflective coatings in photovoltaics to optical waveguides. This work also reports a first comparative study of SixTi1−xO2 films prepared by thermal (T-) and plasma-enhanced (PE-) ALD with varying Si composition and deposition temperatures. Deposition rates of 0.67–0.92 Å/cycle were obtained for SixTi1−xO2 films with x = 0.5–0.91 deposited using PE-ALD at 250 °C, which were higher than that of T-ALD at 200 °C (0.42–0.05 Å/cycle). PE-ALD also exhibited a high deposition rate of 0.81 Å/cycle for SixTi1−xO2 film with x = 0.91 at a low growth temperature of 150 °C. The PE-ALD Si-rich silica–titania films show substantially lower (100×) leakage current densities than the thermally deposited films, along with higher breakdown fields for decreasing deposition temperature. A dielectric constant as low as ∼5 was achieved for PE-ALD SixTi1−xO2 films with high Si (x = 0.91) content. [ABSTRACT FROM AUTHOR]