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.

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We have found a hole trap related to hydrogen and carbon in p-type crystalline silicon after hydrogen and deuterium injection by chemical etching and plasma exposure. It was found from deep-level transient spectroscopy that this center is located at 0.33 eV above the valence band and shows no Poole–Frenkel effect in electric fields lower than 6×103 V/cm. The depth profiling technique using deep-level transient spectroscopy indicated that this center is distributed over the range 1–7 μm from the surface with densities of 1011–1013 cm−3, depending on the hydrogenation method. On the other hand, secondary ions mass spectroscopy revealed that the majority of deuterium injected into silicon exists within a much shallower region less than 60 nm from the surface with higher densities of 1018–1020 cm−3. We have therefore concluded that the majority of injected hydrogen stays in the near-surface region probably in the form of a molecule and larger clusters and only the minority diffuses into the bulk in an atomic form to form an electrically active complex with carbon. We performed annealing experiments to investigate the thermal stability of the complex. It was stable in the dark up to 100 °C, above which it was completely annihilated in first-order kinetics with an activation energy of about 1.7 eV. The illumination of band gap light with and without a reverse bias at room temperature and at 50 °C induced no effect on the stability of the trap. This is contrast to the photoinduced annihilation of a recently observed electron trap related also to hydrogen and carbon and with comparable thermal stability in n-type silicon. These similarities and differences between the two traps and the comparison of the present results with the recently published theoretical calculations of the total energy of hydrogen configurations in the hydrogen-carbon complex suggest that the previously observed electron trap and the presently observed hole trap arise from two different defects with similar origins and structures and are tentatively ascribed to the electronic states of ‘‘bond-centered’’ and ‘‘anti-bonding of carbon’’ configurations of hydrogen in the hydrogen-carbon complex, respectively.

We have evaluated hydrogen and deuterium diffusivities in silicon below room temperature (220–270 K) by analyzing the kinetics of photoinduced dissociation of a chemical etching introduced hydrogen (deuterium)–carbon complex. Under sufficiently strong illumination, the annihilation rate of the complex was proportional to the phosphorus density, indicating that the rate-determining step is the diffusion of hydrogen (deuterium) to phosphorus atoms. Applying the diffusion-controlled reaction theory, we have evaluated the diffusion coefficients as 7×10−2exp(−0.54 eV/kT) cm2 s−1 for hydrogen and 5×10−3exp(−0.49 eV/kT) cm2 s−1 for deuterium, being in good agreement with the extrapolation of the high-temperature diffusion data of A. Van Wieringen and N. Warmoltz [Physica 22, 849 (1956)].

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