Abstract

Orthorhombic II–IV nitride semiconductors offer an expanded and more tunable material set with unique properties, while maintaining close compatibility with the wurtzite crystal structure of the III-nitrides. In particular, MgSiN2—a II–IV nitride closely lattice matched to GaN and AlN—has a band gap suitable for photonic applications in the UV-C wavelength region. MgSiN₂ is also a promising candidate to exhibit ferroelectricity, which has only been observed in very few nitride materials. This study builds on our previous work on the metal-organic chemical vapor deposition (MOCVD) of MgSiN₂ thin films grown on GaN-on-sapphire and c-plane sapphire substrates by exploring higher growth temperature windows, resulting in higher crystalline quality and improved interfaces. Correlations between the growth conditions (Mg:Si precursor molar flow rate ratio, reactor pressure, and growth temperatures from 900 °C to 960 °C) and the resultant film quality are investigated for films grown on GaN-on-sapphire. High-resolution transmission electron microscopy (HR-TEM) reveals high-quality orthorhombic single-crystal MgSiN2, confirming successful epitaxial growth on GaN. Optical transmittance measurements indicate the direct band gap is 6.34-6.36 eV and indirect band gap is 5.77-5.81 eV, affirming the realization of an ultrawide-band gap II–IV nitride semiconductor that is structurally compatible with existing III-nitride device platforms.

Abstract

Orthorhombic II–IV nitride semiconductors offer an expanded and more tunable material set with unique properties, while maintaining close compatibility with the wurtzite crystal structure of the III-nitrides. In particular, MgSiN2—a II–IV nitride closely lattice matched to GaN and AlN—has a band gap suitable for photonic applications in the UV-C wavelength region. MgSiN₂ is also a promising candidate to exhibit ferroelectricity, which has only been observed in very few nitride materials. This study builds on our previous work on the metal-organic chemical vapor deposition (MOCVD) of MgSiN₂ thin films grown on GaN-on-sapphire and c-plane sapphire substrates by exploring higher growth temperature windows, resulting in higher crystalline quality and improved interfaces. Correlations between the growth conditions (Mg:Si precursor molar flow rate ratio, reactor pressure, and growth temperatures from 900 °C to 960 °C) and the resultant film quality are investigated for films grown on GaN-on-sapphire. High-resolution transmission electron microscopy (HR-TEM) reveals high-quality orthorhombic single-crystal MgSiN2, confirming successful epitaxial growth on GaN. Optical transmittance measurements indicate the direct band gap is 6.34-6.36 eV and indirect band gap is 5.77-5.81 eV, affirming the realization of an ultrawide-band gap II–IV nitride semiconductor that is structurally compatible with existing III-nitride device platforms.

Abstract

Orthorhombic II–IV nitride semiconductors offer an expanded and more tunable material set with unique properties, while maintaining close compatibility with the wurtzite crystal structure of the III-nitrides. In particular, MgSiN2—a II–IV nitride closely lattice matched to GaN and AlN—has a band gap suitable for photonic applications in the UV-C wavelength region. MgSiN₂ is also a promising candidate to exhibit ferroelectricity, which has only been observed in very few nitride materials. This study builds on our previous work on the metal-organic chemical vapor deposition (MOCVD) of MgSiN₂ thin films grown on GaN-on-sapphire and c-plane sapphire substrates by exploring higher growth temperature windows, resulting in higher crystalline quality and improved interfaces. Correlations between the growth conditions (Mg:Si precursor molar flow rate ratio, reactor pressure, and growth temperatures from 900 °C to 960 °C) and the resultant film quality are investigated for films grown on GaN-on-sapphire. High-resolution transmission electron microscopy (HR-TEM) reveals high-quality orthorhombic single-crystal MgSiN2, confirming successful epitaxial growth on GaN. Optical transmittance measurements indicate the direct band gap is 6.34-6.36 eV and indirect band gap is 5.77-5.81 eV, affirming the realization of an ultrawide-band gap II–IV nitride semiconductor that is structurally compatible with existing III-nitride device platforms.

Abstract

Orthorhombic II–IV nitride semiconductors offer an expanded and more tunable material set with unique properties, while maintaining close compatibility with the wurtzite crystal structure of the III-nitrides. In particular, MgSiN2—a II–IV nitride closely lattice matched to GaN and AlN—has a band gap suitable for photonic applications in the UV-C wavelength region. MgSiN₂ is also a promising candidate to exhibit ferroelectricity, which has only been observed in very few nitride materials. This study builds on our previous work on the metal-organic chemical vapor deposition (MOCVD) of MgSiN₂ thin films grown on GaN-on-sapphire and c-plane sapphire substrates by exploring higher growth temperature windows, resulting in higher crystalline quality and improved interfaces. Correlations between the growth conditions (Mg:Si precursor molar flow rate ratio, reactor pressure, and growth temperatures from 900 °C to 960 °C) and the resultant film quality are investigated for films grown on GaN-on-sapphire. High-resolution transmission electron microscopy (HR-TEM) reveals high-quality orthorhombic single-crystal MgSiN2, confirming successful epitaxial growth on GaN. Optical transmittance measurements indicate the direct band gap is 6.34-6.36 eV and indirect band gap is 5.77-5.81 eV, affirming the realization of an ultrawide-band gap II–IV nitride semiconductor that is structurally compatible with existing III-nitride device platforms.