The properties of Si surfaces treated in HF solution of various concentrations are characterized by photoluminescence (PL). The Si surfaces treated in 4.5%-HF solution show higher PL intensity than thermally oxidized Si, indicating low surface recombination velocity of the HF-treated Si surface. The effect of ambient gases on HF-treated Si surfaces is studied. The temporal variation of PL intensity is such that it shows an abrupt rise in nitrogen followed by saturation, and the saturated intensity shows only a slight change with time. In air or in oxygen, HF-treated Si shows a gradual or fast rise in PL intensity followed by saturation for a short period and the PL intensity eventually decreases with time presumably due to generation of recombination centers. It is suggested that the oxidation of HF-treated Si induces the formation of recombination centers at the surface.

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Formation of shallow donors has been studied in 100 keV hydrogen-implanted n-type silicon with a dose of 1 × 10 15 cm −2 . Annealing experiments are made in the temperature range 100 to 800 • C for 30 min. Gold Schottky contacts are fabricated on these samples to obtain carrier profiles. The hydrogen profiles are measured by secondary-ion mass spectroscopy. The zero-bias depletion layer width measured at 90 K is below the pre-implantation value in the annealing temperature range 300 to 500 • C, indicating the introduction of shallow donors. Two kinds of shallow donor (HS1 and HS2) are found to be formed in this annealing temperature range from carrier profile measurements. The HS1 donor is observed at the annealing temperatures around 300 • C and shows a concentration peak at the depth around the mean projected range of implanted hydrogen. The HS2 donor is observed in the annealing temperature range 350 to 450 • C and spreads toward the surface with almost flat profiles. Comparison of carrier and hydrogen profiles indicates that the HS1 donor is hydrogen related. The possibility that the HS2 donor is also hydrogen related is discussed.

Commerically available, Czochralski-grown (CZ), phosphorus-and boron-doped (100) silicon wafers have been characterized by capacitance-voltage and deep-level transient spectroscopy measurements of Schottky diodes. Two electron traps labelled A1 (E, -0.10 eV) and A2 (E, -0.13 eV) are commonly observed in n-type wafers with a concentration around 10" ~m -~. These correspond to the hydrogen-related complexes previously repofled. A decrease of carrier concentration occurs near the surface in p-type wafers. This is ascribed to the passivation of boron acceptors by hydrogen. These results indicate that hydrogen is incorporated near the surface in commercial CZ silicon wafers.