Thin Film Synthesis of Semiconductors in the Mg–Sb–N Materials System

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 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
(28ε0) and low hole effective masses (0.9m0), 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 toward understanding semiconductor
properties and chemical trends in the Mg–Sb–N materials
system, paving the way to future practical applications of these novel
materials.