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Keywords:

Si nanowires, interface defects, ESR, annealing, Science & Technology, Physical Sciences, Physics, Applied, Physics, SILICON NANOWIRES, PARAMAGNETIC DEFECTS, OXYGEN VACANCY, DEGRADATION, SI/SIO2, (100)SI/SIO2, GENERATION, CENTERS, PROTON, STATES, 01 Mathematical Sciences, 02 Physical Sciences, 09 Engineering, Applied Physics, 40 Engineering, 49 Mathematical sciences, 51 Physical sciences

Abstract:

Extensive low-temperature (T) electron spin resonance studies (ESR) have been carried out on as-fabricated, vacuum annealed, and irradiated single crystalline arrays of Si nanowires (NWs) with a top diameter of 5 nm produced by top down etching into (100)Si, finally thinned down by high-T oxidation. This reveals the presence of a substantial inherent density of Pb0 (Si3≡Si•) interface defects (charge trapping and recombination centers) quite above standard thermal values, leaving NW-Si/SiO2 interfaces of reduced electrical quality with, consequently, negative influence on the efficiency of passivation of defects by H. The inherent interface quality appears limited by the wire-narrowing thermal oxidation procedure. Vacuum annealing (~610 °C) is found to generally reduce, to more or lesser extent, the Pb0 density to a common value over all samples studied, which result directly counters the presence of inadvertent passivation of defects by H. Rather, the anneal appears to effectuate some interface healing. Short term (<~2 h) UV and VUV (10.02 eV) irradiation has little effect in general, with perhaps some weak increase of Pb1 defects induced by UV photons. On the basis of the observed E0_ defect properties, the chemical vapor deposited Si NW inter space filling Si oxide (200 _C) is found to be OH enriched.