Effective Electron-hole Separation Research Articles

Modified Titania in the Photo-Assisted Oxidation of Chloroform

Degussa P-25 TiO2 powder was used as a catalyst in the photocatalytic oxidation of organics. With the objective of promoting a more effective electron-hole separation upon irradiation, the catalyst was modified with small amounts of platinum. Characterisation of the powders was done by X-Ray diffraction and SEM. Chloroform was used as a model molecule and its degradation followed using selective electrodes, with excellent results for the modified titania. Langmuir-Hinselwood kinetic was used to describe the heterogeneous oxidation of chloroform on TiO2, for low solute concentrations.

Relation between Structural Parameters and the Effective Electron–Hole Separation in InGaN/GaN Quantum Wells

Relation between Structural Parameters and the Effective Electron–Hole Separation in InGaN/GaN Quantum Wells

Relation between Structural Parameters and the Effective Electron-Hole Separation in InGaN/GaN Quantum Wells

The photoluminescence (PL) of InGaN/GaN quantum well (QW) structures is measured as a function of biaxial strain to study the dependence of the luminescence emission on the built-in electric field. The direction and magnitude of the shift in luminescence energy with strain reveals an effective e-h separation in the well. We have used this method to evaluate the effective e-h separation in a number of structures with varying QW thickness and indium content. Our results show that the e-h separation increases with increasing QW thickness and with increasing indium content.

Effect of electron-hole separation on the Landau-level photoluminescence in layered structures in a tilted magnetic field: Magneto-Stark effect

We show that the photoluminescence (PL) intensities of the interband transitions between the electron and hole Landau levels (n{sub e},n{sub h}=0,1,{hor_ellipsis}) in a perpendicular magnetic field B{sub {perpendicular}} are modulated strongly by a superimposed in-plane field B{sub {parallel}} in type-II quantum wells due to electron-hole separation: B{sub {parallel}} suppresses the intensities of the n{sub e}{r_arrow}n{sub h}=n{sub e} diagonal transitions initially and generates n{sub e}{r_arrow}n{sub h}{ne}n{sub e} off-diagonal transitions that are forbidden at B{sub {parallel}}=0. The intensities oscillate at higher B{sub {parallel}}. An additional electric field E{sub {parallel}} parallel to B{sub {parallel}} modifies the effective B{sub {parallel}} and introduces a magneto-Stark shift in the PL line. This new Stark shift requires B{sub {parallel}}{ne}0 unlike the ordinary Stark shift in perpendicular E{sub {perpendicular}}. {copyright} {ital 1998} {ital The American Physical Society}