Silicon- and Graphene-based FETs for THz technology

[EN] This Thesis focuses on the study of the response to Terahertz (THz) electromagnetic radiation of different silicon substrate-compatible FETs. Strained-Si MODFETs, state-of- the-art FinFETs and graphene-FETs were studied. The first part of this thesis is devoted to present the results of an experimental and theoretical study of strained-Si MODFETs. These transistors are built by epitaxy of relaxed-SiGe on a conventional Si wafer to permit the fabrication of a strained-Si electron channel to obtain a high-mobility electron gas. Room temperature detection under excitation of 0.15 and 0.3 THz as well as sensitivity to the polarization of incoming radiations were demonstrated. A two-dimensional hydrodynamic-model was developed to conduct TCAD simulations to understand and predict the response of the transistors. Both experimental data and TCAD results were in good agreement demonstrating both the potential of TCAD as a tool for the design of future new THz devices and the excellent performance of strained-Si MODFETs as THz detectors (75 V/W and 0.06 nW/Hz0.5). The second part of the Thesis reports on an experimental study on the THz behavior of modern silicon FinFETs at room temperature. Silicon FinFETs were characterized in the frequency range 0.14-0.44 THz. The results obtained in this study show the potential of these devices as THz detectors in terms of their excellent Responsivity and NEP figures (0.66 kV/W and 0.05 nW/Hz0.5). Finally, a large part of the Thesis is devoted to the fabrication and characterization of Graphene-based FETs. A novel transfer technique and an in-house-developed setup were implemented in the Nanotechnology Clean Room of the USAL and described in detail in this Thesis. The newly developed transfer technique enables to encapsulate a graphene layer between two flakes of h-BN. Raman measurements confirmed the quality of the fabricated graphene heterostructures and, thus, the excellent properties of encapsulated graphene. The asymmetric dual grating gate graphene FET (ADGG-GFET) concept was introduced as an efficient way to improve the graphene response to THz radiation. High quality ADGG-GFETs were fabricated and characterized under THz radiation. DC measurements confirmed the high quality of graphene heterostructures as it was shown on Raman measurements. A clear THz detection was found for both 0.15 THz and 0.3 THz at 4K when the device was voltage biased either using the back or the top gate of the G-FET. Room temperature THz detection was demonstrated at 0.3 THz using the ADGG-GFET. The device shows a Responsivity and NEP around 2.2 mA/W and 0.04 nW/Hz0.5 respectively at respectively at 4K. It was demonstrated the practical use of the studied devices for inspection of hidden objects by using the in-house developed THz imaging system

Room-Temperature Terahertz Detection and Imaging by Using Strained-Silicon MODFETs

This chapter reports on an experimental and theoretical study of Schottky-gated strained-Si modulation-doped field-effect transistors (MODFETs) with different sub-micron gate lengths (100, 250, and 500 nm). Room-temperature detection of terahertz (THz) radiation by the strained-Si MODFETs was performed at two frequencies (0.15 and 0.3 THz). A technology computer-aided design (TCAD) analysis based on a two-dimensional hydrodynamic model (HDM) was used to investigate the transistor response to THz radiation excitation. TCAD simulation was validated through comparison with DC and low-frequency AC measurements. It was found that the photoresponse of the transistors can be improved by applying a constant drain-to-source bias. This enhancement was observed both theoretically and experimentally. The HDM model satisfactorily describes the experimental dependence of the photoresponse on the excitation frequency, the gate bias, and the drain-to-source current bias. The coupling of the incoming THz radiation to the MODFETs was studied at 0.15 and 0.3 THz. Finally, to demonstrate the suitability of strained-Si MODFET for terahertz applications, an image sensor within a pixel-by-pixel terahertz imaging system for the inspection of hidden objects was used

Quantum nanoconstrictions fabricated by cryo-etching in encapsulated graphene

More than a decade after the discovery of graphene, ballistic transport in nanostructures based on this intriguing material still represents a challenging field of research in two-dimensional electronics. The presence of rough edges in nanostructures based on this material prevents the appearance of truly ballistic electron transport as theo\-re\-tically predicted and, therefore, not well-developed plateaus of conductance have been revealed to date. In this work we report on a novel implementation of the cryo-etching method, which enabled us to fabricate graphene nanoconstrictions encapsulated between hexagonal boron nitride thin films with unprecedented control of the structure edges. High quality smooth nanometer-rough edges are characterized by atomic force microscopy and a clear correlation between low roughness and the existence of well-developed quantized conductance steps with the concomitant occurrence of ballistic transport is found at low temperature. In par\-ti\-cu\-lar, we come upon exact 2$e^{2}/h$ quantization steps of conductance at zero magnetic field due to size quantization, as it has been theoretically predicted for truly ballistic electron transport through graphene nanoconstrictions

Responsivity enhancement of a strained silicon field-effect transistor detector at 0.3 THz using the terajet effect

[EN] We report on the enhancement of responsivity by more than one order of magnitude of a silicon-based sub-terahertz detector when a mesoscopic dielectric particle was used to localize incident radiation to a sub-wavelength volume and focus it directly onto the detector. A strained-silicon modulation field-effect transistor was used as a direct detector on an incident terahertz beam at 0.3 THz. A systematic study in which Teflon cubes were placed in front of the detector to focus the terahertz beam was performed. In this study, cubes with different sizes were investigated, and an enhancement of the responsivity up to 11 dB was observed for a cube with an edge length of 3.45 mm (or 3.45 lambda). Electromagnetic simulation results were in good agreement with the experimental ones and demonstrated that the size of the mesoscopic particle plays an important role in focalizing the electric field within an area below the diffraction limit. This approach provides an efficient, uncostly, and easy to implement method to substantially improve the responsivity and noise equivalent power of sub-terahertz detectors.Tomsk Polytechnic University Development Program; Ministerio de Ciencia, Innovacion y Universidades (PID2019-107885GB-C32, RTI2018-097180-B-100, TEC2016-78028-C3-3-P); Junta de Castilla y Leon (SA121P20, SA256P18); Conselleria d'Educacio, Investigacio, Cultura i Esport (AIC0/2019/018); European Regional Development Fund; Fundacja na rzeczNauki Polskiej (CENTERA-IRA MAB/2018/9)Minin, IV.; Minin, OV.; Salvador-Sánchez, J.; Delgado-Notario, JA.; Calvo-Gallego, J.; Ferrando Bataller, M.; Fobelets, K.... (2021). Responsivity enhancement of a strained silicon field-effect transistor detector at 0.3 THz using the terajet effect. Optics Letters. 46(13):3061-3064. https://doi.org/10.1364/OL.43117530613064461

Comprehensive characterization of Gunn oscillations in In0.53Ga0.47As planar diodes

[EN]In this work, In0.53Ga0.47As planar Gunn diodes specifically designed for providing oscillations at frequencies below 30 GHz have been fabricated and characterized. Different types of measurements were used to define a set of consistent methods for the characterization of the oscillations that can be extended to the sub-THz frequency range. First, negative differential resistance and a current drop are found in the I–V curve, indicating the potential presence of Gunn oscillations (GOs), which is then confirmed by means of a vector network analyzer, used to measure both the S11 parameter and the noise power density. The onset of unstable GOs at applied voltages where the negative differential resistance is hardly visible in the I–V curve is evidenced by the observation of a noise bump at very low frequency for the same applied voltage range. Subsequently, the formation of stable oscillations with an almost constant frequency of 8.8 GHz is observed for voltages beyond the current drop. These results have been corroborated by measurements performed with a spectrum analyzer, which are fully consistent with the findings achieved by the other techniques, all of them applicable to Gunn diodes oscillating at much higher frequencies, even above 300 GHz.Spanish MINECO through project TEC2017-83910-R and the Junta de Castilla y León and FEDER through projects SA022U16 and SA254P18

Phonon-mediated room-temperature quantum Hall transport in graphene

The quantum Hall (QH) effect in two-dimensional electron systems (2DESs) is conventionally observed at liquid-helium temperatures, where lattice vibrations are strongly suppressed and bulk carrier scattering is dominated by disorder. However, due to large Landau level (LL) separation (~2000 K at B = 30 T), graphene can support the QH effect up to room temperature (RT), concomitant with a non-negligible population of acoustic phonons with a wave-vector commensurate to the inverse electronic magnetic length. Here, we demonstrate that graphene encapsulated in hexagonal boron nitride (hBN) realizes a novel transport regime, where dissipation in the QH phase is governed predominantly by electron-phonon scattering. Investigating thermally-activated transport at filling factor 2 up to RT in an ensemble of back-gated devices, we show that the high B-field behaviour correlates with their zero B-field transport mobility. By this means, we extend the well-accepted notion of phonon-limited resistivity in ultra-clean graphene to a hitherto unexplored high-field realm.Comment: 17 pages, 4 figures. Supplementary information available at https://doi.org/10.1038/s41467-023-35986-

Differentiation stage of myeloma plasma cells: biological and clinical significance

[EN] The notion that plasma cells (PCs) are terminally differentiated has prevented intensive research in multiple myeloma (MM) about their phenotypic plasticity and differentiation. Here, we demonstrated in healthy individuals (n = 20) that the CD19 − CD81 expression axis identifies three bone marrow (BM)PC subsets with distinct age-prevalence, proliferation, replication-history, immunoglobulin-production, and phenotype, consistent with progressively increased differentiation from CD19+CD81+ into CD19 − CD81+ and CD19 − CD81 − BMPCs. Afterwards, we demonstrated in 225 newly diagnosed MM patients that, comparing to normal BMPC counterparts, 59% had fully differentiated (CD19 − CD81 −) clones, 38% intermediate-differentiated (CD19 − CD81+) and 3% less-differentiated (CD19+CD81+) clones. The latter patients had dismal outcome, and PC differentiation emerged as an independent prognostic marker for progression-free (HR: 1.7; P = 0.005) and overall survival (HR: 2.1; P = 0.006). Longitudinal comparison of diagnostic vs minimal-residual-disease samples (n = 40) unraveled that in 20% of patients, less-differentiated PCs subclones become enriched after therapy-induced pressure. We also revealed that CD81 expression is epigenetically regulated, that less-differentiated clonal PCs retain high expression of genes related to preceding B-cell stages (for example: PAX5), and show distinct mutation profile vs fully differentiated PC clones within individual patients. Together, we shed new light into PC plasticity and demonstrated that MM patients harbouring less-differentiated PCs have dismal survival, which might be related to higher chemoresistant potential plus different molecular and genomic profiles

Generation and control of non-local chiral currents in graphene superlattices by orbital Hall effect

Graphene-based superlattices offer a new materials playground to exploit and control a higher number of electronic degrees of freedom, such as charge, spin, or valley for disruptive technologies. Recently, orbital effects, emerging in multivalley band structure lacking inversion symmetry, have been discussed as possible mechanisms for developing orbitronics. Here, we report non-local transport measurements in small gap hBN/graphene/hBN moir\'e superlattices which reveal very strong magnetic field-induced chiral response which is stable up to room temperature. The measured sign dependence of the non-local signal with respect to the magnetic field orientation clearly indicates the manifestation of emerging orbital magnetic moments. The interpretation of experimental data is well supported by numerical simulations, and the reported phenomenon stands as a formidable way of in-situ manipulation of the transverse flow of orbital information, that could enable the design of orbitronic devices.Comment: 5 pages, 5 figures and supplementary informatio

Anales de Edafología y Agrobiología Tomo 48 Número 5-12

A comparative study of the effect of soil boron on yield, yield attributes and nutrient uptake by susceptible and tolerant varieties of wheat. Por B. R. Chhipa and P. Lal.-- Suelos y vegetación de las Peñas de Aya (Navarra y Guipúzcoa. Por J. Peralta, J. Íñiguez y J. C. Bascones.-- Presencia de horizonte plácico en Ñadis (Placaquands) y Trumaos (Placudands) en el sur de Chile. Por W. Luzio, C. Barros, M. Aroncibia y S. Alcayaga.-- Retención de 0,0-Dimetil, S-(Z, Metilamino- 2, Oxoetil -Ditiofosfato (Dimetoato) por Vermiculitas homoionicas. l.-cinética del proceso. Por C. Valenzuela Calahorro, A. García Rodríguez y A. Bernalte García.-- Estudio edafogenético en suelo~ de Rañas. Distribución de hierro y aluminio. Por Mª P. García Rodr(guez, J. Forteza Bonnin, y L. F. Lorenzo Martín.-- Water retention equations and their relationship with particle size distribution and bulk density for undisturbed samples. Por A. Andriulo, N. Amiotti y C. Pecorari.-- Evolución regresiva de diversos parámetros edáficos en agroecosistemas (Cafetales, cañaverales) derivados del bosque mesófilo de montaña (México). Por N. García Calderón, F. Velasco y N. Aguilera.-- Micronutrients distribution in grown soils (Fe and Zn) prediction equations of contenta. Por A. Ruiz-Nieto, E. Barahona, S. Jaime, F. Huertas, A. Aguilar and J. Linares.-- Contenido de azufre total en muestras superficiales de suelos de la provincia de la Coruña. Por A. Merino García, C. Monterroso Martínez y E. García -Rodeja G.-- Aspectos termodinámicos de la adsorción de Clorprofan por suelos. Por G. Dios Cancela, J. A. Guillén Alfara y S. González García.-- Consideraciones acerca de las interralaciones entre suelos. Vegetación y paleoprocesos morfogenéticos en el Macizo de Ayllón y la Sierra de Alto Rey (Sector oriental del Sistema Central). Por J. J. Ibáñez Martín, F. Fernández González y A. García Alvarez.--Composición Geoquímica de unas ferricretas en el entorno de un monte isla de Ciudad Real. Por R. Jiménez Ballesta, A. M. Alvarez González, A. Gutiérrez Maroto y E. Redondo.--Relación entre algunas propiedades físico-químicas y las fracciones de fósforo en suelos naturales de Galicia (NW España). Por Mª C. Trasar Cepeda, F. Gil Sotres y F. Guitián Ojea.-- Respuesta del cultivo de tomate en enarenado y condiciones salinas a diferentes programas de fertilización fosfórica. Por M. J. Sarro, A. Saa, C. Cadahía y A. Masaguer.-- Distribución del fósforo en perfiles de suelos de Galicia (NW Spain). Por M. a C. Trasar Cepeda, F. Gil Sotres y F. Guitián Ojea.-- Influencia de la dilución en la desorción de cationes en Andosoles y suelos ándicos. Por C. D. Arbelo, J. E. García-Hernández y J. M. Hernández Moreno.-- Las marismas del Guadalquivir, reserva biogenética de plantas tolerantes a la salinidad. Por T. Marañón, L. V. García, J. M. Murillo y L. Clemente.-- Efectos del Abonado N/K sobre el contenido, interacciones y evolución del N, K, Ca y Mg en varias etapas del desarrollo de la patata. Por M. J. Lema Gesto y A. M. Cortizas.-- Estabilidad estructural de suelos afectados por sales: Revisión bibliográfica. Por E. Amezketa y R. Aragües.-- Descomposición de rastrojo de trigo, respiracion y biomasa microbiana bajo labranza convencional y siembra directa. Por O. J. Santanatoglia, R. Alvarez, P. E. Daniel, G. M. Brazzola y R. García.-- Factores formadores y características generales de los Luvisoles desarrollados sobre materiales calizos y su distribución en la provincia de Valencia. Por Mª D. Soriano Soto.-- Propiedades de intercambio iónico en tobas sálicas pumíticas del sur de la Isla de Tenerife. Por J. E. García Hernández, J. S. Notario del Pino y M. González Martín.-- Las reacciones lentas del fósforo en suelos gallegos: III. Experiencias de incubación: b) Comparación de las técnicas Bray II, Olsen y electroultrafiltración (EUF) para reflejar las variaciones con el tiempo en la extracción de fósforo. Por E. de Blas Varela, F. Gil Sotres y F. Guitián.-- Crecimiento y producción de genotipos procedentes de Haploides de Nicotiana tabacum L. seleccionados en cámara de bajo contenido en C02. Por E. Delgado y H. Medrano.-- Características foliares de genotipos de Nicotiana tabacum L. obtenidos a partir de Haploides seleccionados por supervivencia a bajas concentraciones de C02. Por E. Delgado y H. Medrano.-- Efecto de las poliaminas sobre la actividad fosfatasa ácida y ribonucleasa soluble en semillas de Garbanzo (Cicerarietinum L.). Por E. Merlo, T. Angosto y A. J. Matilla.-- Efectos de la 6-Bencil- aminopurina y el ácido Indol-3-Butfrico en cultivos in vitro de explantos de Hipocotilo-Epicotilo de Pinus canariensis Chr. Sm. ex DC. Por J. F. Pérez Francés, A. Bueno Marrero, V. M. García Díaz y R. Martín.-- Factores abióticos definitorios del área ocupada por Cytisus multiflorus (L 'Her) Sweet en España. Por E. V. Martínez Ropero, J. M. Gómez Gutiérrez y P. Galindo Villardon.-- Índice de satisfacción de los requerimientos hídricos de los cereales de invierno para una región marginal de secano. Por J. D. Paoloni.-- Effect of qualities of irrigation water and NPK fertilizars on grain and straw yield of wheat. Por R. Lal and P.Lal.-- Efecto de la concentración y tipo de agente solidificante del medio de cultivo en la vitrificación de brotes adventicios de Pinus canariensis. Por C. Martínez Pulido.-- Evolución de constituyentes químicos y de la emisión de etileno durante el desarrollo y maduración del albaricoque (Prunus armemízca, L. cv. Búlida). Por A. Amaros, M. Serrano, F. Riquelme y F. Romojaro.-- Cambio varietal en melocotoneros improductivos. Por J. Egea CaballeroPeer reviewe