Improvement of the Photoluminescence Dead Layer Model in III–V Semiconductors

Abstract

It is shown that the photoluminescence (PL) dead layer model, which is widely used in the literature to fit the variations of the room temperature PL intensity versus the surface recombination velocity of III–V compound semiconductor materials, may not be suitable to practical experimental condition. It is proposed a simple analytical derivation of the PL yield which includes the contribution of radiative recombination in the near surface field region.

The Measure of TiO2 Photocatalytic Efficiency and the Comparison of Different Photocatalytic Titania

“…The second-order scavenging reactions of scavengers compete with inhomogeneous radical−radical reactions, which usually depend on the local concentrations at the surface. Therefore, the product yields depend not only on the nature of the scavenger, photocatalyst, surface area, and reactant concentration, but also on the light intensity. − …”

“…This is particularly the case when different procedures for preparation of TiO 2 are involved. Even in the cases where quantum yields are reported, ,− , Φ cannot serve as a general measure for the photocatalytic quality of the photocatalyst because it changes with the specific working conditions such as added solute, solute concentration, wavelength of illumination, layer thickness, light intensity, as well as suspension and sol concentrations. The diverging results, particularly when different laboratories are compared, led to the common assumption that the properties of TiO 2 nanocrystallites strongly depend on accidental impurities and may change by minor uncontrolled variation of conditions.…”