Abstract
In this paper, a data processing method is employed to improve the uniqueness of the electronic transport parameters (the carrier lifetime, carrier diffusion coefficient, and front and rear surface recombination velocities) obtained from fitting free carrier absorption data of silicon wafers. By employing the mean square variance graph or map, the influence of initial values on multi-parameter estimation greatly decreases. Theoretical simulations are performed to investigate the dependence of the uniqueness of the estimated parameters on the number of free parameters by choosing different initial values during multi-parameter fitting. Simulation and experimental results show that the proposed method can significantly improve the uniqueness of the fitted electronic transport parameters.
Highlights
Electronic transport parameters, i.e., the carrier bulk lifetime (τ), diffusion coefficient (D), and front and rear surface recombination velocities (S1 and S2), are important parameters to characterize semiconductors and provide useful information for device fabrication
It can be seen from Eq (1) that modulated FCA (MFCA) signals depend on the electronic transport parameters of the sample
We first discuss the uniqueness of the carrier transport parameter estimates in the traditional MFCA measurements
Summary
Electronic transport parameters, i.e., the carrier bulk lifetime (τ), diffusion coefficient (D), and front and rear surface recombination velocities (S1 and S2), are important parameters to characterize semiconductors and provide useful information for device fabrication. Various non-destructive and non-contact diagnostic methodologies, such as photoconductance decay (PCD), photoluminescence (PL), photothermal radiometry (PTR), free carrier absorption (FCA), and photocarrier radiometry (PCR), have been developed to determine the electronic transport properties of silicon wafers. In all these techniques, the electronic transport properties are simultaneously determined by fitting the experimental data to corresponding rigorous theoretical models via a multi-parameter fitting procedure. In this paper, taking the determination of the electronic transport parameters by modulated FCA (MFCA) as an example, a novel data process method is proposed to improve the uniqueness of the fitted transport parameters. We propose the mean square variance graph or map method and verify its feasibility by both simulation and experiment
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