Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN

Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1–6)10²⁰ cm³ range. In this letter, we show that magnesium nitride (Mg_xN_y) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc_1-xMg_xN thin-film alloys (a) are substitutional solid solutions without Mg_xN_y precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2x10²⁰ cm³ and a hole mobility of 21 cm²/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate Mg_xN_y doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (Mn_xN_y) doping.