Terahertz Plasmon-Resonant Microship Emitters and their Possible Sensing and Spectroscopic

Applications

Taiichi Otsuji, Yuki Tsuda, Tsuneyoshi Komori, Abdelouahad El Fatimy, Tetsuya Suemitsu RIEC: Research Institute of Electrical Communication

Tohoku University Sendai, Japan

otsuji@riec.tohoku.ac.jp

Abstract— This paper reviews recent advances in emission of terahertz (THz) radiation utilizing two-dimensional plasmons in semiconductor heterostructures and their possible sensing and spectroscopic applications. The device is introduced as a light source into a Fourier-transform THz spectrometer. Water-vapor absorption lines as well as fingerprints of honey and maple syrup of suger-group materials were successfully observed.

I. INTRODUCTION In the research of modern terahertz (THz) electronics,

development of compact, tunable and coherent sources operating at THz frequencies is one of the hottest issues [1]. Two-dimensional (2D) plasmons in submicron transistors have attracted much attention due to their nature of promoting emission of electromagnetic radiation in the THz range. Therefore different devices/structures of micron and submicron sizes supporting low-dimensional plasmons were intensively studied as possible candidates for solid-state far-infrared (FIR)/THz sources [1–15]. Mechanisms of plasma wave excitation/emission can be divided (by convention) into two types: (i) incoherent and (ii) coherent type. The first is related to thermal excitation of broadband nonresonant plasmons by hot electrons [2–7]. The second is related to the plasma wave instability mechanisms like Dyakonov–Shur Doppler-shift model [8] and/or Ryzhii-Satou-Shur transit-time model [16, 17], where coherent plasmons can be excited either by hot electrons or by optical phonon emission under near ballistic electron motion [18].

Historically, first experimental observations of THz emission from 2D plasmons involved the first incoherent mechanism: the radiative decay of hot plasmons. Many authors proposed the radiative decay of grating–coupled 2D plasmons in semiconductor heterostructures as one of the most promising candidates for tunable solid-state FIR/THz sources [2-8, 12]. THz emission from hot 2D plasmons has been observed from selectively doped GaAs/AlGaAs hetero-

structures as well as Si metal-oxide semiconductor field effect transistors. In spite of its potential applications, only cryogenic-temperature (4K) emitters were reported [2-7]. THz emission from coherent plasmon excitations in both cryogenic and room temperatures were also studied [9-11, 19-22]. Room temperature THz emission interpreted in terms of Dyakonov-Shur instability was observed from nanometer size GaInAs and GaN/AlGaN high electron mobility transistors (HEMT’s) [9-11].

This paper reviews recent advances in emission of terahertz (THz) radiation utilizing two-dimensional plasmons in semiconductor heterostructures and their possible sensing and spectroscopic applications. First, we propose an original 2D-plasmon-resonant microchip emitter featured with a interdigitated dual-grating gates structure [23, 24]. Room-temperature 0.5-6.5-THz emission from self-oscillating 2D plasmons under the DC-biased and/or optically excited conditions is realized in InGaP/InGaAs/GaAs heterostructure material systems [25-33]. A double-deck 2D-electron layered structure is then introduced into an original dual-grating-gate HEMT to improve the radiation power. The upper-deck 2D electron channel is etched out to form semiconducting dual-grating gate electrodes replacing conventional metallic gate electrodes, succeeding in enhancement of the emission power to beyond microwatts (by one order of magnitude) [28, 32-34].

Next, we demonstrate the applicability of the plasmon-resonant microchip emitter to the broadband THz spectroscopic measurement [34]. First, the field emission property of the double-deck HEMT-type microchip emitter is characterized by using a Fourier-transformed far-infrared spectrometer (FTIR). Then, the microchip emitter is introduced into the FTIR system in place of a commercially-available high-pressure mercury lamp. Atmospheric water vapor and several sugar groups are chosen as samples under measurement. The potentiality of the microchip emitter as a broadband THz light source is examined.

978-1-4244-5335-1/09/$26.00 ©2009 IEEE 1991 IEEE SENSORS 2009 Conference

II. DEVICE STRUCTURE AND OPERATION Figure 1 illustrates the cross section of the plasmon-

resonant emitter [23]. The device structure is based on a HEMT and incorporates (i) interdigitated dual-grating gates (G1 and G2) that periodically localize the 2D plasmon in stripes on the order of 100 nm with a micron-to-submicron interval and (ii) a vertical cavity structure in between the top grating plane and a THz mirror at the backside. The structure (i) works as a THz antenna and (ii) works as an amplifier.

When the DC drain-to-source bias VDS is applied, 2D electrons are accelerated to produce a constant drain-to-source current IDS. Due to such a distributed plasmonic cavity systems in periodic 2D electron-density modulation, the DC current flow may excite the plasma waves in each plasmonic cavity. As shown in Fig. 2, asymmetric cavity boundaries make plasma-wave reflections as well as abrupt change in the density and the drift velocity of electrons, which may cause the current-driven plasmon instability [8, 12, 16, 17] leading to excitation of coherent resonant plasmons. Thermally excited hot electrons also may excite incoherent plasmons [4, 7, 31]. The grating gates act also as THz antenna that converts non-radiative longitudinal plasmon modes to radiative transverse electromagnetic modes [2, 3, 6, 12, 23].

Once the THz electromagnetic waves are produced from the seed of plasma waves, downward-propagating electromagnetic waves are reflected at the mirror back to the plasmon region so that the reflected waves can directly excite the plasmon again according to the Drude optical conductivity [23]. When the intersubband energies for conduction electrons meet the THz photon energy, THz photon absorption may change the dynamic energy distribution spectrum of

conduction electrons so that the intersubband transition process may also help excite the plasmons. When the plasmon resonant frequency satisfies the standing-wave condition of the vertical cavity, the THz electromagnetic radiation will reinforce the plasmon resonance in a recursive manner. Therefore, the vertical cavity may work as an amplifier if the gain exceeds the cavity loss. The quality factor of the vertical cavity is relatively low as is simulated in [23], since the 2D plasmon grating plane of one side of the cavity boundary must have a certain transmittance for emission of radiation. Thus, the cavity serves a rather broadband response.

III. DESIGN AND FABRICATION Field emission properties of the dual-grating-gate

plasmon-resonant emitters are characterized by the structure dependent key parameters as is described in [23]. The primary parameter that initiates the plasmon resonance is the plasma frequency, i.e. plasmon characteristic frequency, of the periodically confined gated plasmon cavities. Each cavity is connected by the connecting portion whose carrier density must be controlled to be far apart from that in the plasmon cavity to make a good plasmon confinement. Thus, this connecting portion has its characteristic frequency. The final parameter is the vertical cavity resonance.

According to the operating frequency band, the grating geometry (single plasmon cavity length and periodicity) and the vertical cavity size are optimally designed. As a fundamental design criterion to obtaining high quantum efficiency the plasmon frequencies of the grating gate electrode and vertical cavity resonance (or its harmonics) are matched to the primary parameter of the plasmonic cavity frequency. It is important to remark that a semiconducting material must be introduced as the grating gate electrode to satisfy the condition.

The device was fabricated with InGaP/InGaAs/GaAs material systems in a double-deck HEMT with semiconducting 2D electron gas (2DEG) grating gates [28, 32, 33]. The schematic device cross section and its SEM image are shown in Fig. 4. The 2D plasmon layer is formed with a lower-deck quantum well at the heterointerface between a 15-nm thick InGaAs channel layer and a 60-nm thick, InGaP

Figure 1. Device cross section for typical GaAs-based heterostructure

material systems. Ex: the electric field (linear polarization), kTHz: the wave vector of electromagnetic radiation. (after Ref. 26.)

Figure 2. Schematic band diagram and operation mechanism.

Figure 3. Cross sectional structure and SEM image of a semiconducting

grating-gate plasmon-resonant emitter. (after Ref. 25.)

1992

carrier-supplying layer. The upper-deck InGaAs channel, serving as the dual grating-gate electrodes, periodically etched to form the uncapped region where the 2DEG concentration becomes lower than the capped region without any external gate bias. For the source/drain ohmic contacts, AuGe/Ni was lifted off and annealed after the upper-deck HEMT was selectively etched. The intrinsic device area has geometry of 30 μm x75 μm, where the grating pattern is replicated on the upper-deck HEMT layer. The grating consists of 150-nm lines and 1850-nm lines aligned alternately with a spacing of 100 nm. The number of fingers is 37 (38) for the 1500-nm (1850-nm) grating. The substrate thickness was 260 μm, corresponding to the fundamental vertical cavity resonance of 80 GHz and the odd harmonics with a 160-GHz spacing.

IV. EXPERIMENTAL RESULTS AND DISCUSSION

A. THz Emission Properties of the Microchip Emitter FTIR measurements were carried to characterize the THz

emission property of the fabricated device [34]. Figure 4

shows the experimental setup and emitter sample installation. The microchip emitter die was mounted on a quartz substrate. The contact pads on the die were electrically interconnected to the biasing metal lines patterned on the substrate via gold bonding wires. The substrate was attached into a dedicated sample holder. Then the sample holder was installed into the FTIR chamber. The electromagnetic radiation from the device was introduced to the Martin-Pupplett interferometer room and led to a liquid-He cooled Si bolometer. The responsivity and noise-equivalent power (NEP) of the detector are 2.84x105 V/W-1 and 1.16x10-13 W/Hz-1/2, respectively. The experimental procedure is as follows; first the background radiation under turning-off the device to be measured, then the radiation with device turned on to be measured. The spectrum of the first-step measurement contains the 300K blackbody radiation modified by the spectral functions of all the elements inside the chamber. Thus, in order to extract the contents of the real emission by the active operation of the device, the spectrum of the second-step measurement is normalized to the first-step one.

Typical measured spectra for a sample having grating finger sizes (Lg1, Lg2) of Lg1/L g2 = 150 nm/1850 nm for different drain-bias conditions are shown in Fig. 5. One can see relatively broad spectra starting from 0.5 THz with maxima around 3.0 THz. The emission dies off abruptly around 6.5 THz, which is thought to be due to the Reststrahlen band of optical phonon modes of the InGaAs channel [31]. The emission intensity is not linear function of the applied VDS bias, thus the drain current, but close to a quadratic function with a threshold property [31]. The maximum emission power at VDS = 12.0 V is estimated to be on the order of 1 μW at 300K. Taking account of the monitored power consumption of the order of 100 mW, the energy conversion efficiency (from DC to THz) is on the order of 10-5.

Idealistic coherent plasmon modes originated from Dyakonov-Shur and/or transit-time-driven instabilities [8, 16, 17] should result in sharp emission peaks on the spectra. The realistic operating condition of the device electrically biased at room temperature, however, arises additional spectral broadening effects. Thermally excited incoherent plasmons [31] and dispersion of the plasmon-resonant frequency depending on the drain bias potential [32, 33] contribute to

(a)

(b)

(c)

Figure 4. Experimental FTIR setup and microchip emitter installation. (a) Block diagram of the FTIR system, (b) emitter chip mounted on a sample

holder installed in the chamber, (c) 2 mm x 10 mm die (accommodating 32 independent emitter devices) mounted on a quartz substrate. (after Ref. 34.)

Figure 5. FTIR measured emission spectra for a dual-grating-gate double-deck HEMT sample having Lg1/Lg2 = 150 nm/1850 nm at room temperature.

(after Ref. 29.)

1993

broaden the emission spectra.

The fine spectral profile exhibits a longitudinal-mode-like vibration. One can consider a Fabry-Perot vertical cavity in between the plasmonic plane (open) and the backside surface (short) boundaries. The substrate thickness of 260 μm gives the longitudinal modes (odd harmonics) in a 160-GHz distance, which perfectly coincides with the observed periodicity of the fine spectral modes. Since the plasmonic cavity must have high emissivity of its main role, the reflection coefficient of the plasmonic plane is relatively low so that an insufficient quality factor of the vertical cavity leads to such a multi-mode emission.

The emission spectral profile of the fabricated device was compared to that of a standard water-cooled high-pressure mercury lamp used as a THz light source in FTIR systems. Fig 6 plots the typical results [34]. It is clearly seen that the main lobe of the emission spectra of the fabricated device stays around 1 to 6 THz, which is far apart from and lower than that for the mercury lamp. The emission spectrum of the mercury lamp traces the black-body radiation due to its nature of thermally heated emission so that the emission at lower THz region is substantially weakened.

Emission power intensity of the mercury lamp in the THz region of our interest is about 30 times higher than that for a single-chip plasmon emitter at the sacrifice of huge power consumption (three orders of magnitude higher than that for a single-chip emitter). It is possible for the plasmon emitters to easily boost the emission power by orders of magnitude by

implementing in an arrayed structure with reasonable power consumption. Preliminary trial of multi-chip operation was carried out [34]. As seen in Fig. 4(c) the wire-bonded two independent emitter devices on a single die were electrically biased at Vds = 9.0 V to operate simultaneously. Figure 7 demonstrates that the dual-chip operation can almost double the emission intensity. The plasmon emitter device may also bring easy-to-operate facility without any water cooling. From the above investigation, the plasmon-resonant emitter has a competitive potentiality to the THz spectroscopic measurement.

B. Application of Emitter Chis to the Spectroscopic Measurement The plasmon-resonant microchip emitter was introduced

into the FTIR system in place of the mercury lamp and examined its applicability as a broadband THz light source. Atmospheric water vapor and several sugar groups, whose identical absorption/transmission spectra co-exist in the emission spectral range available from the emitter, are chosen as samples under measurement.

First, the atmospheric water-vapor absorption was measured [34]. The experimental procedure was as follows; first we measured the emission spectra in vacuum inside the spectrometer as the reference. Then the atmospheric air was introduced into the spectrometer and we performed the identical measurement. The obtained result was normalized to the reference data. Figure 8 shows the measured absorption spectrum of the water vapor. The result ranging from 1 to 6.5 THz well coincides with the spectrum data provided by NASA [35].

Next, we measured the transmission spectra of two different types of sugar groups: honey and maple syrup, both of which contain featured spectrum in the THz region [34]. Figures 9(a) and (b) plot the results measured by using the plasmon-resonant emitter (this work) and by using a high-pressure mercury lump, and their main component(s) provided by RIKEN [36]. The measured samples: honey and maple syrup were in liquid, but the components of sugar groups measured by RIKEN were in dry pellets. Thus, comparison of the absorption peak points among them does not make sense.

Figure 6. FTIR measured emission spectra: the plasmon-resonant emitter

vs. a high-pressure mercury lamp. (after Ref. 34.)

Figure 7. Dual chip operation almost doubles the emission power. VDS =

9.0 V. (after Ref. 34.)

Figure 8. Measured absorption spectrum of atmospheric water vapor in

comparison with the data provided by NASA [35]. (after Ref. 34.)

1994

However, the molecular structures may reflect on the overall spectral shape. They clearly exhibit identical spectral features for both materials. The major bumps for measured each spectrum fairly correspond to those for the main components for each: (a) honey vs. glucose and fructose and (b) maple syrup vs. sucrose. Other minor part of ingredients and/or impurities may also perturb the spectral shape. Compared with a high-power mercury lamp, the plasmon-resonant microchip emitter yields higher noise on the spectra due to weak emission intensity, Further improvements on its emission power will be feasible as is described before, which enables the device to be of promising candidate as a new THz light source.

V. CONCLUSION The application of our original 2D-plasmon-resonant THz

emitters to the spectrum field was examined. The structure is based on a high-electron-mobility transistor and featured with interdigitated dual-grating gates. The dual grating gates can alternately modulate the 2D electron densities to periodically distribute the plasmonic cavities along the channel, acting as an antenna. The device can emit broadband THz radiation even at room temperature from self-oscillating 2D plasmons under the DC-biased conditions. We observed and characterized broadband THz emission with maxima around 3.0 THz from the device. The mechanism of the self-

oscillating broadband emission was interpreted as multiple modes of plasmon excitations including DC-current-driven plasmon instability as well as thermally excited incoherent plasmons. Currently, maximum available emission power from a single device is of the order of 1μW with a DC-to-THz power conversion efficiency of 10-5. We proved that the device is more effective to the spectrum measurement in a low THz frequency range rather than a standard high-pressure mercury lamp if the emission power was multiplied by integration. Feasibility of boosting the emission power by multiple chip operation was also confirmed. The microchip emitter was introduced into a FTIR spectrometer as a light source and successfully identified the atmospheric water vapor absorption lines as well as transmission finger prints for two types of sugar groups: honey and maple syrup. In conclusion the dual-grating-gate plasmon-resonant microchip emitter is well suited for spectroscopic measurement in a low THz area around 0.5 to 6.5 THz. Further improvements on its emission power enable the device to be of promising candidate as a new THz light source.

ACKNOWLEDGMENT The authors thank Prof. T. Asano of Kyushu University

and Prof. Y.M. Meziani of Salamanca University for their contribution and Prof. V. Ryzhii of University of Aizu, Prof. M. Dyakonov of Universite Montpellier II, Dr. W. Knap of CNRS, Montpellier II and Prof. V. Popov of Salatov University for their valuable discussion and encouragement. This work was financially supported in part by the SCOPE Programme from the MIC, Japan, and by the Grant in Aid for Scientific Research (S) from the JSPS, Japan. A part of this work has been carried out at the Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication in Tohoku University.

REFERENCES [1] M. Tonouchi, "Cutting-edge terahertz technology," Nature Photon. 1,

97-105 (2007). [2] R. A. Hopfel, E. Vass, and E. Gornik, "Thermal Excitation of Two-

Dimensional Plasma Oscillations," Phys. Rev. Lett. 49, 1667-1671 (1982).

[3] D. C. Tsui, E. Gornik and R. A. Logan, "Far infrared emission from plasma oscillations of Si inversion layers," Solid State Communications. 35, 875-877 (1980).

[4] N. Okisu, Y. Sambe, and T. Kobayashi, "Far-infrared emission from two-dimensional plasmons in AlGaAs/GaAs heterointerfaces," Appl. Phys. Lett. 48, 776 (1986).

[5] R. Hopfel, G. Lindemann, E. Gornik, G. Stangl, A. C. Gossard and W. Wiegmann, "Cyclotron and plasmon emission from two-dimensional electrons in GaAs," Surf. Sci. 113, 118-123 (1982).

[6] R.J. Wilkinson, C.D. Ager, T. Duffield, H.P. Hughes, D.G. Hasko, H. Armed, J.E.F. Frost, D.C. Peacock, D.A. Ritchie, A.C. Jones, C.R. Whitehouse, and N. Apsley, "Plasmon excitation and self-coupling in a bi-periodically modulated two-dimensional electron gas," J. Appl. Phys., 71, 6049-6061(1992).

[7] K. Hirakawa, K. Yamanaka, M. Grayson and D. C. Tsui, "Far-infrared emission spectroscopy of hot two-dimensional plasmons in Al0.3Ga0.7As/GaAs heterojunctions," Appl. Phys. Lett. 67, 2326 (1995).

[8] M. Dyakonov and M. Shur, "Shallow water analogy for a ballistic field effect transistor: New mechanism of plasma wave generation by dc current," Phys. Rev. Lett. 71, 2465-2468 (1993).

(a)

(b)

Figure 9. Transmission spectra of sugar groups measured by using a plasmon-resonant emitter (this work) and by using a high-pressure mercury lump, and their main ingredient(s) provided by RIKEN [36]. (a) honey vs.

glucose and fructose, and (b) maple syrup vs. sucrose. (after Ref. 34.)

1995

[9] W. Knap, J. Lusakowski, T. Parenty, S. Bollaert, A. Cappy, V. V. Popov, and M. S. Shur, "Terahertz emission by plasma waves in 60 nm gate high electron mobility transistors," Appl. Phys. Lett. 84, 2331 (2004).

[10] J. Lusakowski, W. Knap, N. Dyakonova, and L. Varani, "Voltage tunable terahertz emission from a ballistic nanometer InGaAs/InAlAs transistor," J. Appl. Phys. 97, 064307 (2005).

[11] N. Dyakonova, F. Teppe, J. Lusakowski, W. Knap, M. Levinshtein, A. P. Dmitriev, M. S. Shur, S. Bollaert, and A. Cappy, "Magnetic field effect on the terahertz emission from nanometer InGaAs/AlInAs high electron mobility transistors," J. Appl. Phys. 97, 114313 (2005).

[12] S.A. Mikhailov, “Plasma instability and amplification of electromagnetic waves in low-dimensional electron systems,” Phys. Rev. B. 58, 1517-1532 (1998).

[13] P. Bakshi, K. Kempa, A. Scorupsky, C. G. Du, G. Feng, R. Zobl, G. Strasser, C. Rauch, Ch. Pacher, K. Unterrainer, and E. Gornik, "Plasmon-based terahertz emission from quantum well structures," Appl. Phys. Lett. 75, 1685 (1999).

[14] R. Colombelli, F. Capasso, C. Gmachl, A. L. Hutchinson, D. L. Sivco, A. Tredicucci, M. C. Wanke, A. M. Sergent, and A. Y. Cho, "Far-infrared surface-plasmon quantum-cascade lasers at 21.5 µm and 24 µm wavelengths," Appl. Phys. Lett. 78, 2620 (2001).

[15] A. Tredicucci, R. Kohler, L. Mahler, H. E. Beere, E. H. Linfield, and D. A. Ritchie, "Terahertz quantum cascade lasers—first demonstration and novel concepts," Semicond. Sci. Technol. 20, S222-S227 (2005).

[16] V. Ryzhii, A. Satou, and M. Shur, "Plasma Instability and Terahertz Generation in HEMTs Due to Electron Transit-Time Effect," IEICE Trans. Electron. E89-C, 1012 (2006).

[17] V. Ryzhii, A. Satou, M. Ryzhii, T. Otsuji, and M. S. Shur, "Mechanism of self-excitation of terahertz plasma oscillations in periodically double-gated electron channels," J. Phys.: Condens. Matters. 20, 384207 (2008).

[18] V. Ryzhij, N.A. Bannov, and V.A. Fedirko, Fiz. Tekh. Poluprovodn. 8, 769 (1984).

[19] W. Knap, Y. Deng, S. Rumyantsev, and M. S. Shur, "Resonant detection of subterahertz and terahertz radiation by plasma waves in submicron field-effect transistors," Appl. Phys. Lett., 81, 4637 (2002).

[20] T. Otsuji, M. Hanabe and O. Ogawara, "Terahertz plasma wave resonance of two-dimensional electrons in InGaP/InGaAs/GaAs high-electron-mobility transistors," Appl. Phys. Lett. 85, 2119 (2004).

[21] F. Teppe, W. Knap, D. Veksler, and M.S. Shur, "Room-temperature plasma waves resonant detection of sub-terahertz radiation by nanometer field-effect transistor," Appl. Phys. Lett., 87, 052107 (2005).

[22] A. El Fatimy, F. Teppe, N. Dyakonova, W. Knap, D. Seliuta, G. Valusis, A. Shchepetov, Y. Roelens, S. Bollaert, A. Cappy, and S. Rumyantsev, "Resonant and voltage-tunable terahertz detection in InGaAs/InP nanometer transistors," Appl. Phys. Lett. 89, 131926 (2006).

[23] T. Otsuji, M. Hanabe, T. Nishimura and E. Sano, "A grating-bicoupled plasma-wave photomixer with resonant-cavity enhanced structure," Optics Express, 14, 4815 (2006).

[24] M. Hanabe, T. Nishimura, M. Miyamoto, T. Otsuji and E. Sano, "Structure-sensitive design for wider tunable operation of terahertz plasmon-resonant photomixer," IEICE Transactions on Electronics, E89-C, No. 7, pp. 985-992, (2006).

[25] T. Otsuji, Y.M. Meziani, M. Hanabe, T. Ishibashi, T. Uno, and E. Sano, "Grating-bicoupled plasmon-resonant terahertz emitter fabricated with GaAs-based heterostructure material systems," Appl. Phys. Lett. 89, 263502 (2006).

[26] Y. M. Meziani, Y. Otsuji, M. Hanabe, T. Ishibashi, T. Uno and E. Sano, "Room temperature generation of terahertz radiation from a grating-bicoupled device: size effect," Appl. Phys. Lett. 90, pp.061105-1-061105-3 (2007).

[27] Y. M. Meziani, T. Otsuji, M. Hanabe and E. Sano, "Threshold behavior of photoinduced plasmon-resonant self-oscillation in a new interdigitated grating gates device," Japanese Journal of Applied Physics, 46, No. 4B, pp. 2409-2412 (2007).

[28] T. Suemitsu, Yahya M. Meziani, Y. Hosono, M. Hanabe, T. Otsuji, E. Sano, "Novel plasmon-resonant terahertz-wave emitter using a double-decked HEMT structure" 65th Device Research Conference (DRC) Dig., pp. 157-158, Notre Dame, IN, USA, Jun. 18-20, 2007.

[29] T. Otsuji, Y.M. Meziani, M. Hanabe, T. Nishimura, and E. Sano, "Emission of terahertz radiation from InGaP/InGaAs/GaAs grating-bicoupled plasmon-resonant emitter," Solid State Electronics, Vol. 51, Iss. 10, pp. 1319-1327, Oct. 2007.

[30] Y.M. Meziani, M. Hanabe, T. Otsuji, and E. Sano, "Bolometric detection of terahertz radiation from new grating gates device," Physica Status. Solidi (c). 5, 282-285 (2008).

[31] Y.M. Meziani, H. Handa, W. Knap. T. Otsuji, E. Sano, V.V. Popov, G.M. Tsymbalov, D. Coquillat, and F. Teppe, "Room temperature terahertz emission from grating coupled two-dimensional plasmons," Appl. Phys. Lett. 92, 201108 (2008).

[32] T. Nishimura, H. Handa, H. Tsuda, T. Suemitsu, Y.M. Meziani, W. Knap, T. Otsuji, E. Sano, V. Ryzhii, A. Satou, V.V. Popov, D. Coquillat, and F. Teppe, "Broadband Terahertz Emission from Dual-Grating Gate HEMT’s -Mechanism and Emission Spectral Profile," 66th Device Research Conference (DRC) Dig., pp. 263-264, Santa Barbara, CA, USA, Jun. 23-25, 2008.

[33] T. Otsuji, Y. M. Meziani, T. Nishimura, T. Suemitsu, W. Knap, E. Sano, T. Asano, V.V. Popov, "Emission of terahertz radiation from dual-grating-gates plasmon-resonant emitters fabricated with InGaP/InGaAs/GaAs material systems," J. Phys.: Condens. Matters 20, 384206 (2008).

[34] Y. Tsuda, T. Komori, A. El Fatimy, T. Suemitsu, and T. Otsuji, "Application of plasmonic microchip emitters to broadband terahertz spectroscopic measurement," J. Opt. Soc. Am. B 26, 9, A52-A57 (2009).

[35] Jet Propulsion Laboratory, NASA, ”JPL Catalog”, http://spec.jpl.nasa.gov/ftp/pub/catalog/catform.html.

[36] Tera-phtonics Laboratory, RIKEN Sendai, ”THz database,” http://www.riken.jp/THzdatabase.

1996

MAIN MENUCD/DVD HelpSearch CD/DVDSearch ResultsPrintAuthor IndexKeyword IndexTable of Contents