Terahertz response of GaN thin films

Tsai, Tsong-Ru; Chen, Shijie; Chang, Chih-Fu; Hsu, Sheng-Hsien; Lin, Tai‐Yuan; Chi, Cheng–Chung

doi:10.1364/oe.14.004898

Cited by 47 publications

(29 citation statements)

References 30 publications

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“…The simple Drude-model, describing a conductivity response caused by free carriers, observed in bulk n-GaN [10] and n-GaN films [11], fails to explain the observed features here. Deviations from the Drude model in n-GaN films have also been reported [12]. The smaller conductivity for low frequencies and the zero-crossing of the imaginary part of the conductivity at non-zero frequency indicate a non-Drude conductivity response.…”

Section: Experiments and Resultsmentioning

confidence: 81%

Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

Porte

Turchinovich

Cooke

et al. 2009

J. Phys.: Conf. Ser.

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Abstract. Ultrafast carrier dynamics in InGaN/GaN multiple quantum wells is measured by time-resolved terahertz spectroscopy. The built-in piezoelectric field is initially screened by photoexcited, polarized carriers, and is gradullay restored as the carriers recombine. We observe a nonexponential decay of the carrier density. Time-integrated photoluminescence spectra have shown a complete screening of the built-in piezoelectric field at high excitation fluences. We also observe that the terahertz conductivity spectra differs from simple Drude conductivity, describing the response of free carriers, and are well fitted by the Drude-Smith model. IntroductionThe understanding of ultrafast dynamics in group-III nitride based quantum wells is important for the development of wide bandgap semiconductor devices, such as LEDs and lasers in the bluegreen spectral region [1]. In such systems the large, strain-induced built-in piezoelectric field has significant influence on the optical and electronic properties of AlGaN/GaN and InGaN/GaN quantum wells, described by the quantum confined Stark effect (QCSE) [2]. The QCSE will manifest itself by a strong dependence of the transition energy, absorption coefficient and recombination rate on the carrier density in the quantum well [3]. Whereas in a previous terahertz investigated, the dynamics of the absorption coefficient has been studied [4], we will concentrate on the carrier density decay dynamics by using time-resolved terahertz spectroscopy.

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Section: Experiments and Resultsmentioning

confidence: 81%

Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

Porte

Turchinovich

Cooke

et al. 2009

J. Phys.: Conf. Ser.

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“…the real ε (ω) and imaginary ε (ω) parts of dielectric constants can be obtained [4]. The measured dielectric constant ε (ω) and ε (ω) as a function of frequency for Ba x Sr 1-x TiO 3 films are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Terahertz Dielectric Response of Ferroelectric Ba_xSr_1-xTiO₃Thin Films

et al. 2011

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Terahertz time-domain spectroscopy has been used to investigate the dielectric properties of ferroelectric thin Ba x Sr 1-x TiO 3 films in the frequency range of 0.3 to 2.5 THz. The Ba x Sr 1-x TiO 3 films were deposited on (001) MgO substrate by pulsed laser deposition. The measured complex dielectric function was compared with the Cole-Cole relaxation model and agreed well with the theoretical fit.

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“…They used the Kohlrausch model fit which not only provides the mobility of the free carriers in the GaN film but also estimates the relaxation time distribution function and average relaxation time. 146 In the most recent work, the oscillating dielectric function at various temperatures within THz frequencies is obtained by Fang et al in 2015. The concentration, electron lifetime, and temperature dependences of the point defects in GaN thin films were obtained.…”

Section: Thz-time-domain Spectroscopy For Characterization Of Ganmentioning

confidence: 99%

Review of GaN-based devices for terahertz operation

Ahi

2017

Opt. Eng

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Abstract. GaN provides the highest electron saturation velocity, breakdown voltage, operation temperature, and thus the highest combined frequency-power performance among commonly used semiconductors. The industrial need for compact, economical, high-resolution, and high-power terahertz (THz) imaging and spectroscopy systems are promoting the utilization of GaN for implementing the next generation of THz systems. As it is reviewed, the mentioned characteristics of GaN together with its capabilities of providing high two-dimensional election densities and large longitudinal optical phonon of ∼90 meV make it one of the most promising semiconductor materials for the future of the THz emitters, detectors, mixers, and frequency multiplicators. GaNbased devices have shown capabilities of operation in the upper THz frequency band of 5 to 12 THz with relatively high photon densities in room temperature. As a result, THz imaging and spectroscopy systems with high resolution and deep depth of penetration can be realized through utilizing GaN-based devices. A comprehensive review of the history and the state of the art of GaN-based electronic devices, including plasma heterostructure field-effect transistors, negative differential resistances, hetero-dimensional Schottky diodes, impact avalanche transit times, quantum-cascade lasers, high electron mobility transistors, Gunn diodes, and tera field-effect transistors together with their impact on the future of THz imaging and spectroscopy systems is provided.

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Terahertz response of GaN thin films

Cited by 47 publications

References 30 publications

Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

Terahertz Dielectric Response of Ferroelectric Ba_xSr_1-xTiO₃Thin Films

Review of GaN-based devices for terahertz operation

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Terahertz response of GaN thin films

Cited by 47 publications

References 30 publications

Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

Terahertz study of ultrafast carrier dynamics in InGaN/GaN multiple quantum wells

Terahertz Dielectric Response of Ferroelectric BaxSr1-xTiO3Thin Films

Review of GaN-based devices for terahertz operation

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Terahertz Dielectric Response of Ferroelectric Ba_xSr_1-xTiO₃Thin Films