Transformation of deep-level spectrum of irradiated silicon due to hydrogenation under wet chemical etching

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Abstract
The effect of wet chemical etching in acid solutions on the energy spectrum of n- and p-type silicon crystals previously irradiated with high-energy electrons is studied by deep-level transient spectroscopy. It is observed that together with the well known radiation defects a number of novel deep-level centres appear near the etched surface. The depth profiles of the deep-level centres are investigated depending on the irradiation dose and the temperature of subsequent annealing. The novel centres observed are shown to be complexes of radiation defects with the hydrogen atoms which penetrated into the crystal during etching. The origin of some of these centres from the particular vacancy-related defects is established. A simple quantitative description is given of hydrogen atom penetration during the etching and formation of the hydrogen - radiation defect complexes. Based on this analysis, the radius of hydrogen capture to the well known A-centre (vacancy - oxygen complex) is estimated and the centre with an energy level of eV is identified as a complex of the A-centre with two hydrogen atoms.