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标题：Terahertz time-domain ellipsometry with high precision for the evaluation of GaN crystals with carrier densities up to 10 ²⁰ cm ⁻³
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作者：Verdad C. Agulto ; Toshiyuki Iwamoto ; Hideaki Kitahara 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2021
卷号：11
DOI：10.1038/s41598-021-97253-z
语种：English
出版社：Springer Nature
摘要：Gallium nitride (GaN) is one of the most technologically important semiconductors and a fundamental component in many optoelectronic and power devices. Low-resistivity GaN wafers are in demand and actively being developed to improve the performance of vertical GaN power devices necessary for high-voltage and high-frequency applications. For the development of GaN devices, nondestructive characterization of electrical properties particularly for carrier densities in the order of 10 19 cm −3 or higher is highly favorable. In this study, we investigated GaN single crystals with different carrier densities of up to 10 20 cm −3 using THz time-domain ellipsometry in reflection configuration. The p- and s-polarized THz waves reflected off the GaN samples are measured and then corrected based on the analysis of multiple waveforms measured with a rotating analyzer. We show that performing such analysis leads to a ten times higher precision than by merely measuring the polarization components. As a result, the carrier density and mobility parameters can be unambiguously determined even at high conductivities.