Theory And Technology Study On Microscopic Differential Reflectance Spectroscopy For Film Detection

Organic thin film has gained plenty of attentions in the fields of energy,communications and information as a new material structure. With the developmentof organic thin film device, both scientific research and industrial applications requirenew in-situ measurement methods with higher performance such as spatial resolution,faster measurement, et al.. In this thesis, we develop the measurement model ofmicroscopic differential reflectance spectroscopy (MDRS). After that, we propose anew method to carry out MDRS measurement with spatial and spectroscopyinformation obtained synchronously. A home-made MDRS system is developed toinvestigate the properties of organic thin film during the processes of growth,structure evolution and desorption. Main achievements of this research works are thefollowing:First, we propose a set of theoretical system "measurement model-opticalconstant algorithm-result analysis" of MDRS technology for film detection, includingthe following works:1) Based on wave propagation in the medium and interface, a measurementmodel of MDRS is developed. We discuss the model in three different types:sub-monolayer model, three phase model and multi phase model.2) Combining the measurement model and Kramers-Kronig relations of opticalconstant, we present an algorithm, with multiple iterations, to solve the opticalconstant (or dielectric constant) of thin film.3) We proposal the methods to study the deposition and desorption of organicmolecules with MDRS. The difference of optical properties between the singlemolecule and molecular crystal is also discussed. Based on this, we develop how totransfer the optical properties carried out by MDRS, into structure information.Second, we propose a new method to carry out MDRS measurement system. Themeasurement error and pseudo signal are analyzed and compensated to improve theperformance. The works include:1) We develop a MDRS system that bound to the (ultra) high vacuum system,which could obtain spatial and spectroscopy information synchronously.2) We propose an optical structure of two beams which is able to eliminate the measurement error caused by the drift of light intensity of the lamp.3) The pseudo signal caused by the instability of temperature is discussed withexperiment. We propose a measurement method suitable for in-situ investigation thatthe temperature of the substrate varies during the measurement.Third, utilizing the MDRS system, we study the films growth and desorption onthe insulator or metal substrates. Many results are acquired including:1) We investigate the difference of structure and optical properties between themonolayer of different floors, which indicates different intermolecular effects.2) A number of phenomenons preliminarily reveal the law of organic molecularbehaviors such as: deposition, evolution and desorption.