Method and system for measuring optical band gap

Abstract

The invention provides a method and a system for measuring an optical band gap. The method comprises the steps of measuring a to-be-measured sample by adopting an ellipsometer to obtain an ellipsometric data measured value; performing modeling and fitting calculation on the ellipsometric data, judging whether a fitting value obtained through fitting calculation is close to a measured value or not,if the fitting value obtained through fitting calculation is close to the measured value, performing reverse calculation by utilizing dispersion equation parameters obtained through fitting, and acquiring a chromatic dispersion curve of the refractive index and the extinction coefficient of the to-be-measured sample along with the change of the wavelength; acquiring an absorption coefficient of the to-be-measured sample according to the chromatic dispersion curve and an absorption coefficient formula; and solving the optical band gap of the to-be-measured sample according to the absorption coefficient and a Tauc formula. Since the ellipsometer has the features of being high in measurement precision and no requirement on transparency of the substrate material, the measurement of the optical band gap can be precisely realized, and the applicable range of the optical band gap measurement can be greatly expanded; and the method has good measurement effect on the materials such as thin-film material, non-transparent material, multi-layer or complex film structure material and like on the non-transparent substrate or single-side polished substrate.

Description

technical field [0001] The invention relates to the technical field of semiconductor performance detection, and more specifically, to a method and system for measuring an optical bandgap. Background technique [0002] The optical band gap is an important characteristic parameter of semiconductor materials, and its size mainly depends on the energy band structure of the semiconductor, that is, it is related to the crystal structure and the bonding properties of atoms. It reflects how strongly the valence electrons are bound, that is, the minimum energy required to generate intrinsic excitation. The measurement of the optical bandgap is of great significance for the research of the properties of semiconductor materials and the design and development of new optoelectronic devices. [0003] Among them, the optical bandgap of semiconductor materials can be measured by spectroscopic methods. Usually, a UV-visible spectrophotometer is used to measure the absorbance of the sample a...

AI Technical Summary

Problems solved by technology

However, the UV-Vis spectrophotometer has many limitations in practical use: transmission measurement is only suitable for transparent samples, such as liquid samples, transparent bulk samples or transparent film samples coated on transparent and double-sided polished substrates , and it is required to provide a reference sample to remove the background interference, because the reference sample and the actual sample have problems such as processing accuracy error and substrate backside contamination, so it is often difficult to completely exclude the influence of the substrate in the measurement results of thin film samples. The error is large; reflective measurement is mostly used for powder sample testing. For thin film samples, because it cannot remove the interference of substrate reflection, it cannot obtain pure film absorbance, so the optical bandgap value cannot be accurately calculated.

[0004] And so on, due to the above-mentioned many problems in measuring the optical band gap of semiconductor materials by using a UV-visible spectrophotometer, the optical band gap of many new materials (such as opaque materials, thin film materials coated on opaque substrates, etc.) cannot be obtained. Efficient, precise measurements hinder study of properties of semiconductor materials

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