Thermoelectric bolometers based on ultra-thin heavily doped single-crystal silicon membranes

We present ultra-thin silicon membrane thermocouple bolometers suitable for fast and sensitive detection of low levels of thermal power and infrared radiation at room temperature. The devices are based on 40 nm-thick strain tuned single crystalline silicon membranes shaped into heater/absorber area and narrow n- and p-doped beams, which operate as the thermocouple. The electro-thermal characterization of the devices reveal noise equivalent power of 13 pW/rtHz and thermal time constant of 2.5 ms. The high sensitivity of the devices is due to the high Seebeck coefficient of 0.39 mV/K and reduction of thermal conductivity of the Si beams from the bulk value. The bolometers operate in the Johnson-Nyquist noise limit of the thermocouple, and the performance improvement towards the operation close to the temperature fluctuation limit is discussed.Comment: 11 pages, 3 figure

Dispersive readout of reconfigurable ambipolar quantum dots in a silicon-on-insulator nanowire

We report on ambipolar gate-defined quantum dots in silicon on insulator (SOI) nanowires fabricated using a customised complementary metal-oxide-semiconductor (CMOS) process. The ambipolarity was achieved by extending a gate over an intrinsic silicon channel to both highly doped n-type and p-type terminals. We utilise the ability to supply ambipolar carrier reservoirs to the silicon channel to demonstrate an ability to reconfigurably define, with the same electrodes, double quantum dots with either holes or electrons. We use gate-based reflectometry to sense the inter-dot charge transition(IDT) of both electron and hole double quantum dots, achieving a minimum integration time of 160(100) $\mu$s for electrons (holes). Our results present the opportunity to combine, in a single device, the long coherence times of electron spins with the electrically controllable holes spins in silicon.Comment: 5 pages, 4 figure

Reconstructing phonon mean free path contributions to thermal conductivity using nanoscale membranes

Knowledge of the mean free path distribution of heat-carrying phonons is key to understanding phonon-mediated thermal transport. We demonstrate that thermal conductivity measurements of thin membranes spanning a wide thickness range can be used to characterize how bulk thermal conductivity is distributed over phonon mean free paths. A non-contact transient thermal grating technique was used to measure the thermal conductivity of suspended Si membranes ranging from 15 to 1500 nm in thickness. A decrease in the thermal conductivity from 74% to 13% of the bulk value is observed over this thickness range, which is attributed to diffuse phonon boundary scattering. Due to the well-defined relation between the membrane thickness and phonon mean free path suppression, combined with the range and accuracy of the measurements, we can reconstruct the bulk thermal conductivity accumulation vs. phonon mean free path, and compare with theoretical models

Acoustic phonon propagation in ultra-thin Si membranes under biaxial stress field

We report on stress induced changes in the dispersion relations of acoustic phonons propagating in 27 nm thick single crystalline Si membranes. The static tensile stress (up to 0.3 GPa) acting on the Si membranes was achieved using an additional strain compensating silicon nitride frame. Dispersion relations of thermally activated hypersonic phonons were measured by means of Brillouin light scattering spectroscopy. The theory of Lamb wave propagation is developed for anisotropic materials subjected to an external static stress field. The dispersion relations were calculated using the elastic continuum approximation and taking into account the acousto-elastic effect. We find an excellent agreement between the theoretical and the experimental dispersion relations

Phonons in Slow Motion: Dispersion Relations in Ultra-Thin Si Membranes

We report the changes in dispersion relations of hypersonic acoustic phonons in free-standing silicon membranes as thin as \sim 8 nm. We observe a reduction of the phase and group velocities of the fundamental flexural mode by more than one order of magnitude compared to bulk values. The modification of the dispersion relation in nanostructures has important consequences for noise control in nano and micro-electromechanical systems (MEMS/NEMS) as well as opto-mechanical devices.Comment: 5 page

Study and fabrication of nanometer devices for THz applications

Les applications émergentes dans la gamme des fréquences Térahertz (THz, 10¹² Hz) stimulent le développement des composants actifs et passifs rapides ainsi que des émetteurs et des détecteurs de radiation travaillant dans ce domaine. Les dispositifs actuels ne répondent pas à tous les besoins de l'industrie à cause de la consommation, la taille et le coût très importants. La solution pour la réalisation des émetteurs et des détecteurs peut venir des transistors à ondes plasma que nous avons étudiés. Ce sont les composant à base de HEMT Ill-V exploitants les nouvelles propriétés de transport électronique. Les mesures de ces dispositifs ont montré les possibilités de l'émission et de la détection de la radiation autour de 1 THz, à température basse et ambiante. Une détection résonante avec une fréquence ajustable est possible. D'un autre côté il est nécessaire de réaliser les composants actifs électroniques (transistors) capables de fonctionner aux fréquences proches du THz. Ceci est nécessaire pour la réalisation des circuits rapides comme les amplificateurs, les mélangeurs et autres. Pour répondre à cette demande, nous avons étudié deux types de transistors double-grilles. Les mesures ont prouvé l'amélioration des performances statiques et dynamiques (saturation de courant de drain et courant de drain maximal, efficacité de commande, transconductance et conductance de sortie, fréquences de fonctionnement). De plus, la consommation aux performances équivalentes est plus faible. Les simulations montrent que les performances peuvent être améliorées d'avantage.The emergent applications in the Terahertz (THz) frequencies range stimulate the development of active and passive rapid devices as much as of emitters and detectors working in this domain. Actually existent devices do not respond to all industry needs because of too high consumption, size and cost, and other inconvenient. A solution for realisation of emitters and detectors could come from plasma-wave transistor that we studied. These devices are based on 1I1-V HEMT and utilised a particular behaviour of electronic transport. Measurements have shown the possibility of emission and detection of radiation at about 1 THz. From the other hand it is necessary to realize electronic active devices (transistors) able to operate near the THz range. This is necessary for realisation of rapid integrated circuits such as amplifiers, mixers and so on. To do this we have chosen to study two kinds of double-gate transistors. Measurements have shown the increasing of static and dynamic performances (maximum drain current and drain current saturation, efficiency of charge control, transconductance, output conductance, operation frequencies). Besides, the same performances can be obtained at lower consumption. Simulations show that performances could be improved even more

Étude et fabrication de dispositifs nanométriques pour applications THz

Les applications émergentes dans la gamme des fréquences Térahertz (THz, 10 Hz) stimulent le développement des composants actifs et passifs rapides ainsi que des émetteurs et des détecteurs de radiation travaillant dans ce domaine. Les dispositifs actuels ne répondent pas à tous les besoins de l'industrie à cause de la consommation, la taille et le coût très importants. La solution pour la réalisation des émetteurs et des détecteurs peut venir des transistors à ondes plasma que nous avons étudiés. Ce sont les composant à base de HEMT Ill-V exploitants les nouvelles propriétés de transport électronique. Les mesures de ces dispositifs ont montré les possibilités de l'émission et de la détection de la radiation autour de 1 THz, à température basse et ambiante. Une détection résonante avec une fréquence ajustable est possible. D'un autre côté il est nécessaire de réaliser les composants actifs électroniques (transistors) capables de fonctionner aux fréquences proches du THz. Ceci est nécessaire pour la réalisation des circuits rapides comme les amplificateurs, les mélangeurs et autres. Pour répondre à cette demande, nous avons étudié deux types de transistors double-grilles. Les mesures ont prouvé l'amélioration des performances statiques et dynamiques (saturation de courant de drain et courant de drain maximal, efficacité de commande, transconductance et conductance de sortie, fréquences de fonctionnement). De plus, la consommation aux performances équivalentes est plus faible. Les simulations montrent que les performances peuvent être améliorées d'avantage.The emergent applications in the Terahertz (THz) frequencies range stimulate the development of active and passive rapid devices as much as of emitters and detectors working in this domain. Actually existent devices do not respond to all industry needs because of too high consumption, size and cost, and other inconvenient. A solution for realisation of emitters and detectors could come from plasma-wave transistor that we studied. These devices are based on 1I1-V HEMT and utilised a particular behaviour of electronic transport. Measurements have shown the possibility of emission and detection of radiation at about 1 THz. From the other hand it is necessary to realize electronic active devices (transistors) able to operate near the THz range. This is necessary for realisation of rapid integrated circuits such as amplifiers, mixers and so on. To do this we have chosen to study two kinds of double-gate transistors. Measurements have shown the increasing of static and dynamic performances (maximum drain current and drain current saturation, efficiency of charge control, transconductance, output conductance, operation frequencies). Besides, the same performances can be obtained at lower consumption. Simulations show that performances could be improved even more.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF