Abstract
Driven by the need to overcome the physical limits of silicon-based devices during aggressive downscaling, high relative permittivity (high-κ) dielectric materials have become central to semiconductor research. In metal-oxide-semiconductor field-effect transistors (MOSFETs), replacing silicon dioxide (SiO2) with high-κ gate dielectrics is crucial for enhancing gate capacitance while minimizing leakage current. Among potential alternatives, aluminium oxide (Al2O3) offers significant advantages, including high thermal and chemical stability, abundance, low toxicity, high electrical resistivity, and a wide bandgap that yields low leakage and high breakdown strength. However, despite its higher relative permittivity (κ ~9) compared to SiO2 (κ ~3.9), Al2O3 falls short of other high-κ candidates like hafnium oxide (HfO2, κ~20).
This seminar first demonstrates how the dielectric properties of pulsed laser deposited (PLD) Al2O3 thin films are substantially enhanced through optimized Mg-Si co-doping. Specifically, co-doping increases relative permittivity by ~45% while reducing dielectric loss by ~33%. Combined with the high intrinsic resistivity of Al2O3, these improvements enable gate dielectrics with higher capacitance and lower leakage current. This enhancement is driven by the formation of acceptor-donor defect complexes associated with correlated barrier hopping of localized charge carriers.
The second part of the seminar examines the dielectric properties of PLD-grown antimony oxide (Sb2O3) thin films, which exhibit a remarkably high room-temperature relative permittivity of ~140 at 1 kHz. Comprehensive impedance spectroscopy, electric modulus analysis, and conductivity measurements yield mutually consistent results, establishing a coherent understanding of their dielectric behavior.
Anyone interested is welcome to attend.