Articles you may be interested inTemperature dependent dielectric function in the near-infrared to vacuum-ultraviolet ultraviolet spectral range of alumina and yttria stabilized zirconia thin films Mechanisms of several photoluminescence bands in hafnium and zirconium silicates induced by ultraviolet photons J. Appl. Phys. 99, 094106 (2006); 10.1063/1.2199977Photoluminescence from polymer-like hydrogenated and nitrogenated amorphous carbon films Photoluminescence ͑PL͒ spectra induced by ultraviolet photons were measured for amorphous hafnia and zirconia deposited by plasma-enhanced chemical-vapor deposition ͑PECVD͒, amorphous hafnia deposited by pulse laser deposition, and crystalline yttria-stabilized zirconia. Two kinds of samples were prepared for both hafnia and zirconia deposited by PECVD using different source alkoxides in different deposition chambers. A PL peak was observed around 2.8 eV similarly in all hafnia and zirconia samples, irrespective of the difference in crystallinity, oxygen deficiency, source alkoxide, deposition method, or the substrate material. The decay profile of this PL is also similar in all the samples. These facts clearly show that neither impurities, oxygen vacancy, nor defects at the interface between the sample and the substrate are responsible for the PL. It is a luminescence inherent in hafnia and zirconia and is most likely due to radiative recombination between localized states at the band tails. When the samples were annealed in oxygen, a new PL peak appeared around 4.2 eV in all the amorphous samples. Its decay profile is also in common with these samples. Vacuum-ultraviolet absorption measurements and PL excitation measurements indicate that the 4.2-eV PL is excited due to the interband absorption.

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Two photoluminescence (PL) components with peaks around 2.8–3.0 and 3.8eV were induced in hafnium silicates by the irradiation of synchrotron radiation photons at 8.0eV, while two similar ones were induced in zirconium silicates around 2.7–3.0 and 3.8eV. By examining PL excitation spectra, PL decay characteristics, and vacuum-ultraviolet absorption spectra, it is assumed that the origin of the PL component around 2.7(2.8)–3.0eV is the same as that of the PL component around 2.7–2.9eV observed in hafnia and zirconia. In the band gaps of hafnium silicates, zirconium silicates, hafnia, and zirconia, luminescent centers responsible for the PL components around 2.7(2.8)–2.9(3.0)eV have their respective upper and lower states with a certain constant energy difference that does not change by the hafnium or zirconium content. Electrons (or holes) excited by ultraviolet photons to tail states at the band edges first relax to the upper state of the luminescent centers, and then they are deexcited to the lower state, which induces the PL components.

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The gate insulator process for SiC-MOSFET was examined and high-quality interface was realized by employing the pre-annealing process before high-temperature N2 annealing. The pre-annealing evidently activated the interface to introduce nitrogen, and then field-effect mobility exceeded 50 cm2/Vs. The fabricated sample also demonstrated superior bias temperature instability (BTI) and excellent breakdown electric field of 11.7 MV/cm.