Effective control on flat band voltage of epitaxial lanthanide oxide based metal oxide semiconductor capacitors by interfacial carbon

Present work addresses the issue of flat band voltage instability engendered by the presence of large number of fixed charges and interface traps at and close to the interface of metal oxide semiconductor capacitors. We show that submonolayer of C incorporation onto Si surface prior to epitaxial lanthanide oxides (Ln(2)O(3): Gd2O3, Nd2O3) deposition can significantly improve their electrical properties. Ultraviolet photoelectric spectroscopy shows that most of the intrinsic surface states that stem from the dangling bonds on Si surface disappear after passivation with C. The flat band voltage of Pt/Gd2O3/Si MOS capacitors can be tuned in a controlled manner by systematic incorporation of C onto Si surface, effectively at Gd2O3-Si interface. (C) 2013 AIP Publishing LLC

Long-Term Stability of Epitaxial (Nd1-xGdx)(2)O-3 Thin Films Grown on Si(001) for Future CMOS Devices

The (Nd1-xGdx)(2)O-3 thin films were grown on Si(001) in 2005 using molecular beam epitaxy followed by an in vacuo metallization of Pt contacts. Pt/(Nd1-xGdx)(2)O-3/Si(001) metal-oxide-semiconductor structures have been characterized several times over the period of 2005-2015 in order to investigate the stability of their physical and electrical properties. Core-level X-ray photoelectron spectroscopy (XPS) spectra remeasured during 2015 depict that the layer still retains its original properties that were measured in 2005. Although there has been some degradation of electrical properties such as capacitance and leakage current over several years, interestingly the midgap density of interface traps' (D-it) value has been found to be decreased from 1.1x10(12) to 3.5x10(11) eV(-1)cm(-2) over the years. The formation of silicate-like interface inferred from XPS measurements can be attributed to such an improvement over this period. Time-dependent dielectric breakdown measurements under constant current stress and constant voltage stress were also carried out to investigate the reliability of the structure

Epitaxial Gd2O3 on strained Si1-xGex layers for next generation complementary metal oxide semiconductor device application

Strained Si1-xGex (x = 0.1-0.4) layers were grown on Si(111) and Si(001) substrates using molecular beam epitaxy followed by the growth of epitaxial Gd2O3 thin films on Si1-xGex layers using same technique. Pt/Gd2O3/Si1-xGex/Si stacks fabricated by several in situ process steps exhibit excellent electrical properties. Surface and microstructural analysis of both Si1-xGex and Gd2O3 layers carried out by different in situ and ex situ tools reveal a relaxed epi-Gd2O3 layer on a strained Si1-xGex layer on both Si(111) and Si(001) substrates with sharp interfaces between the oxide and the SiGe layer. Standard electrical measurements, such as capacitance-voltage and leakage current analysis, demonstrate promising electrical properties for such metal oxide semiconductor capacitors. A capacitance equivalent thickness as low as 1.20 nm with associated leakage current density of 2.0 mA/cm(2) was obtained for devices with 4.5 nm thin oxide films where the density of interface trap (D-it) was only similar to 10(11) cm(-2) eV(-1). (C) 2013 AIP Publishing LLC