Chemical etching-induced defects in phosphorus-doped silicon

Abstract

We have found with deep-level transient spectroscopy that chemical etching introduced three electron traps, E1(0.11), E2(0.13), and E3(0.15), in the near-surface region of phosphorus-doped crystalline silicon. The results on depth profiles of these traps and carriers suggested the donor character of the traps, but they hardly exhibited the Poole–Frenkel effect. From their correlations with carbon and oxygen, we propose a tentative identification that E1 and E2 traps arise from two kinds of hydrogen-oxygen-carbon complexes and the E3 trap arises from a hydrogen-carbon complex. Hydrogen is assumed to be adsorbed on the silicon surface during chemical etching and diffuse into the interior of the crystal during the subsequent evaporation and sample storage processes to be trapped at two kinds of oxygen-carbon complexes and substitutional carbon to form the traps. The annealing behavior of E2 and E3 traps in the dark were studied in detail. Their densities were increased at temperatures of 70–90 °C and subsequently were decreased at higher temperatures obeying first-order kinetics. The increase in trap densities is interpreted to be due to the further formation of the traps by capturing mobile hydrogen by oxygen-carbon complexes and substitutional carbon. This hydrogen is assumed to be released at temperatures of 70–90 °C by the dissociation of the hydrogen-phosphorus complex that was also formed by in-diffusing hydrogen during the evaporation and sample storage processes. The subsequent decrease in trap densities is attributed to the thermal dissociation of the traps at higher annealing temperatures and the subsequent loss of hydrogen at sinks. The illumination of band-gap light above 230 K annihilated the traps. The annihilation of the traps occurred only outside the depletion region of the Schottky structure. This effect is ascribed to the recombination-enhanced reaction, in which the electronic energy released by the electron-hole recombination at a trap level is converted into local vibrational energy to induce the thermal dissociation of the traps.

Electrical activity of carbon-hydrogen centers in Si

“…These results suggest that (C-H) II is a deep acceptor with a level at E c Ϫ0.16 eV. The acceptor nature of (C-H) II is in disagreement with the conclusions reached by Endrös et al 7 and Kamiura et al 9,19 …”

Chemical etching‐induced defects in n‐type ZnSe crystal grown by physical vapor transport

“…So far some point defects introduced during etching process were reported in crystalline silicon [16,17]. The hydrogen absorbed at the surface of silicon on chemical etching, diffused into the interior of silicon and trapped by the dopant and impurity atoms, and then the hydrogen-related complex defects were generated in silicon [17]. Therefore, we propose tentatively that both E1 and E2 traps arise from hydrogen-related defects.…”

“…These results indicate at this time either defects and/or impurities diffused from the sample surface into the bulk during the chemical etching. So far some point defects introduced during etching process were reported in crystalline silicon [16,17]. The hydrogen absorbed at the surface of silicon on chemical etching, diffused into the interior of silicon and trapped by the dopant and impurity atoms, and then the hydrogen-related complex defects were generated in silicon [17].…”

The Interaction of Hydrogen with Deep Level Defects in Silicon

“…Hydrogen is introduced via wet chemical etching (acid solution) at around room temperature [161,162,163]. The amount of hydrogen introduced is very low and is confined to the surface region.…”