The electrostatics of Ta2O5 in Si-based metal oxide semiconductor devices

Abstract

Thin dielectric layers are a prominent route to control the band alignments and effective work function of metal oxide semiconductor (MOS) devices. In this work, the electrostatic effects of thin Ta2O5 layers on the band alignments of MOS devices are examined. A detailed analysis of the physical properties of a thick (∼6 nm) Ta2O5 layer is reported. No significant dipoles at Ta2O5-Al2O3 and Ta2O5-SiO2 interfaces are found, as well as any significant charges inside Ta2O5 layers. When positioned at the interface, Ta2O5 is shown to prevent the formation of band offsets between Al2O3-SiO2, resulting in a shift of 1 ± 0.2 eV versus samples without interfacial Ta2O5. The relatively large magnitude of this shift in the current experimental configuration compared to previous works may indicate the participation of interface charges in the band offset. The possible use for these effects in devices is discussed.

Oxygen partial pressure induced effects on the microstructure and the luminescence properties of pulsed laser deposited TiO2 thin films

“…. have been employed for the deposition of TiO 2 thin films [9][10][11][12][13] . Among them, pulsed laser deposition (PLD) becomes popular because of the uniform deposition and the fine control of reactive gas in deposition chamber 10,14 .…”

Band offsets at amorphous-crystalline Al2O3–SrTiO3 oxide interfaces

“…The uncertainty in the position of the small contamination peak has negligible effect on the position of the major O 1s component of the Al2O3 film. 46 The distance of the onset of the energy loss tail 47,48 from the major O 1s (Al2O3) peak yields a bandgap of 6.6±0.2 eV (denoted by a horizontal arrow in the inset of Fig. 3).…”

Leakage current characteristics in MOCVD grown InAs quantum dot embedded GaAs metal-oxide-semiconductor capacitor

“…It may be mentioned here that unlike SiO 2 based MOS device, the high-k materials with less thickness leads to signicant reduction in leakage current density while maintaining the same capacitance value. Several reports are available in the literature on various high-k gate dielectrics such as HfO 2 , 17 Al 2 O 3 , 18 TiO 2 , 19 CeO 2 , 20 Y 2 O 3 , 21 Ta 2 O 5 , 22 and rear earth based binary and ternary oxides 23 to ensure good quality and defect free interface with GaAs. Among them ZrO 2 is one of the most promising candidate, which possesses certain advantages such as high dielectric constant ($25), a high break down eld (7-15 MV cm À1 ), large bandgap (5.8 eV), and thermodynamically stable.…”