Photoluminescence in Analysis of Surfaces and Interfaces

Abstract

Photoluminescence (PL) is the spontaneous emission of light from a material under optical excitation. The excitation energy and intensity are chosen to probe different regions and excitation concentrations in the sample. PL investigations can be used to characterize a variety of material parameters. PL spectroscopy provides electrical (as opposed to mechanical) characterization, and it is a selective and extremely sensitive probe of discrete electronic states. Features of the emission spectrum can be used to identify surface, interface, and impurity levels and to gauge alloy disorder and interface roughness. The intensity of the PL signal provides information on the quality of surfaces and interfaces. Under pulsed excitation, the transient PLintensity yields the lifetime of nonequilibrium interface and bulk states. Variation of the PL intensity under an applied bias can be used to map the electric field at the surface of a sample. In addition, thermally activated processes cause changes in PL intensity with temperature. PL analysis is nondestructive. Indeed, the technique requires very little sample manipulation or environmental control. Because the sample is excited optically, electrical contacts and junctions are unnecessary and high‐resistivity materials pose no practical difficulty. In addition, time‐resolved PL can be very fast, making it useful for characterizing the most rapid processes in a material. The fundamental limitation of PL analysis is its reliance on radiative events. Materials with poor radiative efficiency, such as low‐quality indirect bandgap semiconductors, are difficult to study via ordinary PL. Similarly, identification of impurity and defect states depends on their optical activity. Although PL is a very sensitive probe of radiative levels, one must rely on secondary evidence to study states that couple weakly with light.

Effect of Etching Time on Optical and Thermal Properties of p-Type Porous Silicon Prepared by Electrical Anodisation Method

“…The PL spectrum provides the transition energies, which can be used to determine the band gap. PL intensity also related to the rates of radiative and nonradiative recombination rates [25]. Photoluminescence spectroscopy was performed by a Power Technology diode laser, having an excitation wavelength of 405 nm.…”

Sintesis dan Karakterisasi Fotoluminisens Carbon Dots Berbahan Dasar Organik dan Limbah Organik

“…Spektrum PL yang bergantung kepadatan photoeksitasi electron bahan yang mengindikasikan sifat permukaan bahan sehingga sifat dari material bisa dideteksi dengan rinci [4]. Selain itu, spectrum PL menyediakan energi transisi yang dapat digunakan untuk menentukan tingkat energi elektronik berupa enegi gap [5].…”

Radiation Induced Synthesis of In2O3Nanoparticles - Part II: Synthesis of In2O3 Nanoparticles by Thermal Decomposition of Un-irradiated and γ-irradiated Indium Acetylacetonate

“…It is well known from literature that bulk In 2 O 3 cannot emit light at room temperature. However, PL emissions of the nanocrystalline In 2 O 3 samples are possible due to the effect of oxygen vacancies 20 and recently to indium inertial and their associated complex defects 21 . Figure 6 shows the RT-PL spectra of the as-synthesized In 2 O 3 nanoparticles.…”