Silicon crystallizes in the diamond-cubic phase and shows only a weak emission at 1.1 eV. Diamond-hexagonal silicon however has an indirect bandgap at 1.5 eV and has therefore potential for application in opto-electronic devices. Here we discuss a method based on advanced silicon device processing to form diamond-hexagonal silicon nano-ribbons. With an appropriate temperature anneal applied to densify the oxide fillings between silicon fins, the lateral outward stress exerted on fins sandwiched between wide and narrow oxide windows can result in a phase transition from diamond-cubic to diamond-hexagonal Si at the base of these fins. The diamond-hexagonal slabs are generally 5–8 nm thick and can extend over the full width and length of the fins, i.e. have a nano-ribbon shape along the fins. Although hexagonal silicon is a metastable phase, once formed it is found being stable during subsequent high temperature treatments even during process steps up to 1050 ºC.

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A transient leakage current was measured as a function of time for thin (~9 nm) strontium titanate (STO) capacitor dielectrics with RuO x as a bottom electrode and TiN as a top electrode at different temperatures under constant direct current (DC) bias stress. With the space-charge-limited (SCL) current theory, the mobility of oxygen vacancies (V O ) and the activation energy (E 0 ) of V O were extracted. By closely examining the time-zero current-voltage (I-V) curves for a positively and a negatively held DC bias conditions before and after the stresses, an understanding of trap-assisted-tunneling (TAT) current, initiated by oxygen vacancies (V O ) is presented.Based on this understanding, a way to further reduce the leakage current for a sub-10 nm dielectric film is provided.

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