TY - GEN
T1 - Bronsted and Lewis base quenching of photoemission from luminescent `porous silicon'
T2 - Proceedings of the Second Symposium on Dynamics in Small Confining Systems
AU - Chun, J. K M
AU - Bocarsly, Andrew Bruce
AU - Cottrell, T. R.
AU - Benziger, Jay Burton
AU - Yee, J. C.
PY - 1993
Y1 - 1993
N2 - The photoluminescence (PL) observed from porous silicon (PS) is found to be very sensitive to pH. Bronsted bases quench the PL and simultaneously produce a blue shift of the p-type PS emission. Similarly, PL of n-type PS is quenched, but the emission is red shifted. Exposure to acids enhances PL and reverses the quenching due to base exposure. A pKa of 3-4 was determined for PS formed on both n- and p-type substrates, and identifies an acidic surface proton as a primary component in the PL mechanism. Variations in the intensity and energy distribution of PL as a function of temperature suggest that: 1) small changes in the hydration state of the surface may affect the emission, and 2) at least two luminescent species exist on the surface of PS; one of which is pH and temperature sensitive. SO2, a Lewis base, also quenches the PL of p-type PS quickly and reversibly. Exposure to acid is unnecessary for restoration of the PL. In contrast to reactivity with Bronsted bases, the reversibility with SO2 argues for a different quenching mechanism. Preliminary experiments show that PL is significantly quenched, approximately 2-5%, by concentrations of approximately 30 ppm SO2 in Ar.
AB - The photoluminescence (PL) observed from porous silicon (PS) is found to be very sensitive to pH. Bronsted bases quench the PL and simultaneously produce a blue shift of the p-type PS emission. Similarly, PL of n-type PS is quenched, but the emission is red shifted. Exposure to acids enhances PL and reverses the quenching due to base exposure. A pKa of 3-4 was determined for PS formed on both n- and p-type substrates, and identifies an acidic surface proton as a primary component in the PL mechanism. Variations in the intensity and energy distribution of PL as a function of temperature suggest that: 1) small changes in the hydration state of the surface may affect the emission, and 2) at least two luminescent species exist on the surface of PS; one of which is pH and temperature sensitive. SO2, a Lewis base, also quenches the PL of p-type PS quickly and reversibly. Exposure to acid is unnecessary for restoration of the PL. In contrast to reactivity with Bronsted bases, the reversibility with SO2 argues for a different quenching mechanism. Preliminary experiments show that PL is significantly quenched, approximately 2-5%, by concentrations of approximately 30 ppm SO2 in Ar.
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M3 - Conference contribution
SN - 1558991786
T3 - Materials Research Society Symposium Proceedings
SP - 329
EP - 333
BT - Materials Research Society Symposium Proceedings
PB - Publ by Materials Research Society
Y2 - 30 November 1992 through 4 December 1992
ER -