Kilovolt-class β-Ga2O3 field-plated Schottky barrier diodes with MOCVD-grown intentionally 1015 cm−3 doped drift layers

Abstract

We report on the growth optimization of intentionally low-doped (1015 cm−3) high-quality beta-gallium oxide (β-Ga2O3) drift layers of up to 10 μm thick via metalorganic chemical vapor deposition (MOCVD) and the fabrication of kilovolt-class field-plated Schottky barrier diodes on these thick drift layers. Homoepitaxial growth was performed on (010) β-Ga2O3 substrates using trimethylgallium as the Ga precursor. Growth parameters were systematically optimized to determine the best conditions for high-quality thick growths with the given reactor geometry. Chamber pressure was found to improve the growth rate, mobility, and roughness of the samples. Growth rates of up to 7.2 μm/h, thicknesses of up to 10 μm, Hall mobilities of up to 176 cm2/Vs, RMS roughness down to 5.45 nm, UID concentrations as low as 2 × 1015 cm−3, and controllable intentional doping down to 3 × 1015 cm−3 were achieved. Field-plated Schottky barrier diodes (FP-SBDs) were fabricated on a 6.5 × 1015 cm−3 intentionally doped 10 μm thick film to determine the electrical performance of the MOCVD-grown material. The FP-SBD was found to have a current density of >100 A/cm2 at 3 V forward bias with a specific differential on resistance (Ron,sp) of 16.22 mΩ cm2 and a turn-on voltage of 1 V. The diodes were found to have high-quality anode metal/semiconductor interfaces with an ideality factor of 1.04, close to unity. Diodes had a maximum breakdown voltage of 1.50 kV, leading to a punch-through maximum field of 2.04 MV/cm under the anode metal, which is a state-of-the-art result for SBDs on MOCVD-grown (010) drift layers.