Enhanced Er ₂ O ₃ /GaSb Interface Quality via Combined Plasma Treatment and ALD-AlN Passivation Layer

High-quality gate dielectric layers and interfaces between high-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k$</tex-math> </inline-formula> films and substrates are essential for optimal performance and electrical stability of metal–oxide–semiconductor field-effect transistors (MOSFETs). This study demonstrates the efficacy of combining N–H mixed plasma pretreatment and AlN passivation to enhance the interface quality and electrical properties of high-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k$</tex-math> </inline-formula> Er<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>/GaSb metal–oxide–semiconductor (MOS) devices. X-ray photoelectron spectroscopy (XPS) analysis confirmed the N–H mixed plasma removes native interfacial oxides, while AlN suppresses element diffusion and oxidation. Electrical characterization revealed a high dielectric constant of 26.74 and a low leakage current density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.64\times 10{-{7}}$</tex-math> </inline-formula> A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $</tex-math> </inline-formula> cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{-{2}}$</tex-math> </inline-formula> at 1 V. The combined process reduced interface state density by 17%, validated by the conductance method and low-frequency noise (LFN) analysis. Temperature-dependent leakage current analysis identified Schottky emission (SE) [room temparatue (RT)] and Fowler–Nordheim (FN) tunneling [low temperature (LT)] as dominant mechanisms, yielding a low charge carrier effective mass (0.38m<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>) and a high interface potential barrier (0.83 eV). These results confirm that the synergistic process significantly improves interface control and carrier transport.