Terahertz time domain spectroscopy for ultra-high frequency response of gallium oxide

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2021-01-26

{'items': [{'description': {'blocks': [{'key': 'dp6p2', 'text': 'Ga2O3 belongs to a group of materials referred to as ultrawide bandgap semiconductors. It exists in various forms, but the most stable one is the β-Ga2O3 crystal structure. Research on β-Ga2O3 materials is a highly active area nowadays because the β-Ga2O3 semiconductor shows significant potential for high-power and high-voltage devices. ', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [{'offset': 2, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 4, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 150, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 152, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 189, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 191, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 252, 'length': 1, 'style': 'SUBSCRIPT'}, {'offset': 254, 'length': 1, 'style': 'SUBSCRIPT'}], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': 'b28s0', 'term': '1) Gallium oxide (Ga2O3)'}, {'description': {'blocks': [{'key': 'fq986', 'text': 'Semiconductors are often categorized according to their bandgap – a key property that determines their uses and applications. The conventional silicon (Si) semiconductor has a bandgap of 1.12 eV and is commonly used in integrated circuits. Wide-bandgap semiconductors have a larger bandgap, e.g., gallium nitride (GaN) and silicon carbide (SiC) which have bandgaps of 3.4 eV and 3.26 eV, respectively. Semiconductors with wider bandgaps are used in devices that need to operate at higher voltages and temperatures. UWBG semiconductors are those that have a bandgap larger than that of GaN, like β-Ga2O3 which has a bandgap of ~4.8 eV. Such materials are attractive for high-power and high-voltage applications.', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '94q2k', 'term': '2) Ultra-wide bandgap (UWBG) semiconductors'}, {'description': {'blocks': [{'key': 'cbj1c', 'text': 'THz-TDS is a technique that probes material properties using terahertz waves. Unlike ultraviolet light or x-rays, terahertz radiation is nondestructive due to its lower energies. THz-TDS is widely used to characterize the dielectric and electrical properties of semiconductors and other materials in the far-infrared region.', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '59hdc', 'term': '3) Terahertz time-domain spectroscopy (THz-TDS)'}, {'description': {'blocks': [{'key': 'giir', 'text': 'THz waves refer to electromagnetic waves with frequencies in the order of 1012 Hz, specifically in the wavelength region between 3 mm and 30 μm (0.1~10 THz). Aside from their scientific applications like material analysis, THz waves can also be used in technologies such as medical imaging, security screening, and telecommunications. With frequencies higher than radio waves, THz waves can pave the way for high-frequency operation devices and high-speed, ultra-high bandwidth communications. As such, THz is considered key to communication technologies beyond 5G/6G. ', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [{'offset': 76, 'length': 2, 'style': 'SUPERSCRIPT'}], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '6nfie', 'term': '4) Terahertz wave (THz wave)'}, {'description': {'blocks': [{'key': '2msml', 'text': 'Tera Prospector is a general-purpose THz time-domain spectrometer developed by Nippo Precision Co., Ltd. The complex refractive index/permittivity spectra in the terahertz region can be measured accurately using this equipment. In addition to Ga2O3, it can be used for other semiconductors such as Si, SiC and GaN.', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}, {'key': 'dqkq7', 'text': 'https://terahertzwave.com/en/', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '1ptfm', 'term': '5) Tera Prospector'}, {'description': {'blocks': [{'key': 'fcm0o', 'text': 'The complex refractive index is a material property that describes how light propagates through the material. The real part is the refractive index which is related to the speed of propagation, while the imaginary part is the extinction coefficient which indicates how strongly the light is attenuated as it propagates in the material. Light is attenuated when part of the energy is absorbed by the crystal atoms (phonon absorption) or by the free electrons in the material (free carrier absorption). The complex refractive index can also be expressed in terms of permittivity as a function of frequency. ', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '8gimr', 'term': '6) Complex refractive index'}, {'description': {'blocks': [{'key': 'dqp98', 'text': 'The Drude-Lorentz model quantifies the dependence of the complex refractive index and permittivity on the frequency of light, taking into account the effects of phonons and free carriers. This model is commonly used in evaluating semiconductor materials. ', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '7rncs', 'term': '7) Drude-Lorentz model'}, {'description': {'blocks': [{'key': 'cmi68', 'text': 'The static permittivity refers to the permittivity at zero frequency or 0 Hz. ', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': 'el1o', 'term': '8) Static permittivity'}, {'description': {'blocks': [{'key': 'dnei', 'text': 'Hall measurement is a conventional characterization technique to measure the electrical properties of semiconductors. In the Hall method using Van der Pauw configuration, current is applied and voltage is measured with the use metal contacts. ', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '893vu', 'term': '9) Hall measurement'}, {'description': {'blocks': [{'key': 'dtc2a', 'text': 'CV measurements are another conventional technique used to characterize the electrical properties of semiconductors and devices. In this measurement, voltage is applied then the capacitance of the material is measured with varying voltage with the use of electrodes.', 'type': 'unstyled', 'depth': 0, 'inlineStyleRanges': [], 'entityRanges': [], 'data': {}}], 'entityMap': {}}, 'key': '6a34d', 'term': '10) Capacitance-voltage (CV) measurements'}]}

['ile']

['Makoto Nakajima', 'Verdad C. Agulto', 'Valynn Katrine Mag-usara']