scholarly journals Terahertz time-domain ellipsometry with high precision for the evaluation of GaN crystals with carrier densities up to 1020 cm−3

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Verdad C. Agulto ◽  
Toshiyuki Iwamoto ◽  
Hideaki Kitahara ◽  
Kazuhiro Toya ◽  
Valynn Katrine Mag-usara ◽  
...  
Keyword(s):  
Electrical Properties ◽  
High Voltage ◽  
Time Domain ◽  
High Frequency ◽  
Carrier Density ◽  
Power Devices ◽  
Reflection Configuration ◽  
Nondestructive Characterization ◽  
Thz Waves

AbstractGallium 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 1019 cm−3 or higher is highly favorable. In this study, we investigated GaN single crystals with different carrier densities of up to 1020 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.

Characterization of the electrical properties of an InN epilayer using terahertz time-domain spectroscopic ellipsometry

2019 ◽  
Vol 58 (SC) ◽  
pp. SCCB22 ◽  
Author(s):  
Kenta Morino ◽  
Shingo Arakawa ◽  
Takashi Fujii ◽  
Shinichiro Mouri ◽  
Tsutomu Araki ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Spectroscopic Ellipsometry ◽  
Time Domain

scholarly journals Electrical Characterization of a New Crosslinked Copolymer Blend for DC Cable Insulation

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1434 ◽  
Author(s):  
Sarath Kumara ◽  
Xiangdong Xu ◽  
Thomas Hammarström ◽  
Yingwei Ouyang ◽  
Amir Masoud Pourrahimi ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Electric Field ◽  
Surface Potential ◽  
High Voltage ◽  
Direct Current ◽  
Electrical Characterization ◽  
Copolymer Blend ◽  
New Material ◽  
Potential Decay

To design reliable high voltage cables, clean materials with superior insulating properties capable of operating at high electric field levels at elevated temperatures are required. This study aims at the electrical characterization of a byproduct-free crosslinked copolymer blend, which is seen as a promising alternative to conventional peroxide crosslinked polyethylene currently used for high voltage direct current cable insulation. The characterization entails direct current (DC) conductivity, dielectric response and surface potential decay measurements at different temperatures and electric field levels. In order to quantify the insulating performance of the new material, the electrical properties of the copolymer blend are compared with those of two reference materials; i.e., low-density polyethylene (LDPE) and peroxide crosslinked polyethylene (XLPE). It is found that, for electric fields of 10–50 kV/mm and temperatures varying from 30 °C to 70 °C, the DC conductivity of the copolymer blend is in the range of 10−17–10−13 S/m, which is close to the conductivity of crosslinked polyethylene. Furthermore, the loss tangent of the copolymer blend is about three to four times lower than that of crosslinked polyethylene and its magnitude is on the level of 0.01 at 50 °C and 0.12 at 70 °C (measured at 0.1 mHz and 6.66 kV/mm). The apparent conductivity and trap density distributions deduced from surface potential decay measurements also confirmed that the new material has electrical properties at least as good as currently used insulation materials based on XLPE (not byproduct-free). Thus, the proposed byproduct-free crosslinked copolymer blend has a high potential as a prospective insulation medium for extruded high voltage DC cables.

Dielectrophoresis-Based Assembly and High-Frequency Characterization of Carbon Nanotube Bundles

2007 ◽  
Vol 990 ◽  
Author(s):  
Michael Woodson ◽  
Alexander Tselev ◽  
Jie Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electrical Properties ◽  
Electronic Properties ◽  
Integrated Circuit ◽  
High Frequency ◽  
Simple Route ◽  
Full Characterization ◽  
Nanotube Bundles

ABSTRACTAs the size of integrated circuit elements decreases, the properties of carbon nanotubes (CNTs) become increasingly attractive for interconnect applications. To be used by industry, full characterization of the electronic properties of CNT aggregates is essential.Dielectrophoresis from CNTs suspended in liquid has been demonstrated as a simple route to bundles of aligned parallel nanotubes. We describe a method by which circuits including such bundles may be fabricated, and provide some high-frequency measurements of their electrical properties. The contributions of the contacts can be separated from those of the bundle itself.

Characterization of Electrical Properties in SiC Crystals by Raman Scattering Spectroscopy

2008 ◽  
Vol 600-603 ◽  
pp. 501-504 ◽  
Author(s):  
T. Kitamura ◽  
Shinichi Nakashima ◽  
Tomohisa Kato ◽  
K. Kojima ◽  
Hajime Okumura
Keyword(s):  
Electrical Properties ◽  
Raman Scattering ◽  
Shape Analysis ◽  
Line Shape ◽  
Carrier Density ◽  
Peak Frequency ◽  
Bulk Crystals ◽  
Raman Scattering Spectroscopy ◽  
Line Shape Analysis

We characterized the 4H- and 6H-SiC bulk crystals with graded doping and epitaxial films with various carrier densities by Raman scattering spectroscopy. Electrical properties such as free carrier density were examined for the SiC crystals through Raman measurements of the A1 LO-phonon plasmon coupled (LOPC) mode and its line shape analysis. The peak frequency and band width of LOPC mode varied with carrier density in the range from 1016 to 1019 cm-3. The line shape analysis revealed that the carrier density in the SiC crystals can be simply estimated from measured frequency shift of LOPC mode for 4H- and 6H-SiC crystals.

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