Structural and electrical properties of MOCVD-grown scandium nitride thin films on sapphire, Si, GaN, and SiC

Abstract

Investigation of the growth and properties of binary ScN can aid in the understanding of its ferroelectric ternary alloys with GaN and AlN, but there are no existing data for ScN grown by metalorganic chemical vapor deposition (MOCVD). In this work, ScN growth by MOCVD was demonstrated using the Sc precursor (EtCp)2Sc(dbt). A broad range of growth temperatures, pressures, and V/III ratios were tested to investigate the impact of growth parameters on the properties of MOCVD-grown ScN. Approximately 100 nm-thick ScN films with growth rates from 0.06 to 0.20 Å/s were deposited on c-sapphire, (0001) GaN, Si-face 4H-SiC, and (001) Si. X-ray diffraction measurements showed that ScN films were solely (111)-oriented on both sapphire and GaN. Hall effect measurements revealed very high n-type electrical charge in the samples. The carrier concentrations of ScN on sapphire ranged from 2.1 × 1020 to 7.2 × 1020 cm−3, with electron mobilities in the range of 20–7 cm2 V−1 s−1. ScN films on GaN exhibited carrier concentrations from 9.6 × 1019 to 2.5 × 1020 cm−3 and electron mobilities from 42 to 8.5 cm2 V−1 s−1. The lowest sheet resistance of 45 Ω/□ (resistivity of 5.2 × 10−4 Ω-cm) was achieved for an ScN on sapphire film. These results indicate the potential for integrating ScN into the next generation of nitride electronics through MOCVD growth.