Thin film synthesis of semiconductors in the Mg-Sb-N materials system

TL;DR

This study explores the synthesis and properties of new Mg-Sb-N thin film semiconductors, revealing metastable and stable phases with potential optoelectronic and photovoltaic applications through experimental and computational methods.

Contribution

It reports the first synthesis of Mg3SbN in thin film form and characterizes a new Mg2SbN3 nitride, advancing understanding of Mg-Sb-N semiconductors.

Findings

Discovered Mg2SbN3 with wurtzite structure

Synthesized Mg3SbN with antiperovskite structure

Optical absorption onset at 1.3 eV matches theoretical predictions

Abstract

Nitrides feature many interesting properties, such as a wide range of bandgaps suitable for optoelectronic devices including light-emitting diodes (LEDs), and piezoelectric response used in microelectromechanical systems (MEMS). Nitrides are also significantly underexplored compared to oxides and other chemistries, with many being thermochemically metastable, sparking interest from a basic science point of view. This paper reports on experimental and computational exploration of the Mg-Sb-N material system, featuring both metastable materials and interesting semiconducting properties. Using sputter deposition, we discovered a new Mg2SbN3 nitride with a wurtzite-derived crystal structure and synthesized the antimonide-nitride Mg3SbN with an antiperovskite crystal structure for the first time in thin film form. Theoretical calculations indicate that Mg2SbN3 is metastable and has properties relevant to LEDs and MEMS, whereas Mg3SbN has a large dielectric constant (28\epsilon_0) and low hole effective masses (0.9m_0), of interest for photovoltaic solar cell absorbers. The experimental solar-matched 1.3 eV optical absorption onset of the Mg3SbN antiperovskite agrees with the theoretical prediction (1.3 eV direct, 1.1 eV indirect), and with the measurements of room-temperature near-bandgap photoluminescence. These results make an important contribution towards understanding semiconductor properties and chemical trends in the Mg-Sb-N materials system, paving the way to future practical applications of these novel materials.