Magali Estrada

Bio: Magali Estrada is an academic researcher from CINVESTAV. The author has contributed to research in topics: MOSFET & Thin-film transistor. The author has an hindex of 25, co-authored 195 publications receiving 2903 citations. Previous affiliations of Magali Estrada include Instituto Politécnico Nacional.

Accurate modeling and parameter extraction method for organic TFTs

Abstract: In this paper we demonstrate the applicability of the unified model and parameter extraction method (UMEM), previously developed by us, to organic thin film transistors, OTFTs. The UMEM, which has been previously used with a-Si:H, polysilicon and nanocrystalline TFTs, provides a much rigorous and accurate determination of main electrical parameters of organic TFTs than previous methods. Device parameters are extracted in a simple and direct way from the experimental measurements, with no need of assigning predetermined values to any other model parameter or using optimization methods. The method can be applied to both experimental and simulated characteristics of organic TFTs, having different geometries and mobility. It provides a very good agreement between transfer, transconductance and output characteristics calculated using parameter values obtained with our extraction procedure and experimental curves. Differences in mobility behavior, as well as other device features that can be analyzed using UMEM are discussed.

New procedure for the extraction of basic a-Si:H TFT model parameters in the linear and saturation regions

Abstract: A new procedure is proposed to extract basic parameters for the AIM-Spice amorphous thin film transistor model in the above-threshold region. Our method avoids non-linear optimization, which is mainly the method utilized up to now, when using a program extractor included in AIM-Spice. The present extraction procedure is based on the integration of the experimental data current. The integration method as in known is convenient to decrease the effects of experimental noise. The method is applied to the linear and saturation regions for the above-threshold regime and allows the extraction of all the above-threshold parameters. The accuracy of the simulated curves using the parameters extracted with the new procedure is verified with measured and calculated data using the expressions contained in the model.

Compact model for short channel symmetric doped double-gate MOSFETs

Abstract: A new compact model for currents in short channel symmetric double-gate MOSFETs is presented which considers a doped silicon layer in the range of concentrations between 10 14 and 3 � 10 18 cm � 3 . The mobile charge density is calculated using analytical expressions obtained from modeling the surface potential and the difference of potentials at the surface and at the center of the Si doped layer without the need to solve any transcendental equations. Analytical expressions for the current–voltage characteristics are presented, as function of silicon layer impurity concentration, gate dielectric and silicon layer thickness, including variable mobility. The short channel effects included are velocity saturation, DIBL, VT roll-off, channel length shortening and series resistance. Comparison of modeled with simulated characteristics obtained in ATLAS device simulator for the transfer characteristics in linear and saturation regions, as well for as output characteristics, show good agreement within the practical range of gate and drain voltages, as well as gate dielectric and silicon layer thicknesses. The model can be easily introduced in circuit simulators.

Mobility model for compact device modeling of OTFTs made with different materials

Abstract: In this paper we present a new approach to model mobility in organic thin film transistors, OTFTs, which is used to analyze the behavior of mobility in devices made of poly(methyl methacrylate), PMMA, on poly(3-hexylthiophene), P3HT, recently reported by us. It is also used to discuss differences observed between OTFTs made with other polymers and oligomers. The method allows the calculation of the characteristic temperature and energy distribution of localized states (DOS) in the active layer, considering an exponential distribution. It is also shown that using the extracted DOS parameters as input DOS parameters in ATLAS simulator, it is possible to reproduce very well the device characteristics.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

Abstract: Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Low-Voltage Tunnel Transistors for Beyond CMOS Logic

Abstract: Steep subthreshold swing transistors based on interband tunneling are examined toward extending the performance of electronics systems. In particular, this review introduces and summarizes progress in the development of the tunnel field-effect transistors (TFETs) including its origin, current experimental and theoretical performance relative to the metal-oxide-semiconductor field-effect transistor (MOSFET), basic current-transport theory, design tradeoffs, and fundamental challenges. The promise of the TFET is in its ability to provide higher drive current than the MOSFET as supply voltages approach 0.1 V.

MoS2 Field-Effect Transistor for Next-Generation Label-Free Biosensors

Abstract: Biosensors based on field-effect transistors (FETs) have attracted much attention, as they offer rapid, inexpensive, and label-free detection. While the low sensitivity of FET biosensors based on bulk 3D structures has been overcome by using 1D structures (nanotubes/nanowires), the latter face severe fabrication challenges, impairing their practical applications. In this paper, we introduce and demonstrate FET biosensors based on molybdenum disulfide (MoS2), which provides extremely high sensitivity and at the same time offers easy patternability and device fabrication, due to its 2D atomically layered structure. A MoS2-based pH sensor achieving sensitivity as high as 713 for a pH change by 1 unit along with efficient operation over a wide pH range (3–9) is demonstrated. Ultrasensitive and specific protein sensing is also achieved with a sensitivity of 196 even at 100 femtomolar concentration. While graphene is also a 2D material, we show here that it cannot compete with a MoS2-based FET biosensor, which ...

Stability of organic solar cells: challenges and strategies

Abstract: Organic solar cells (OSCs) present some advantages, such as simple preparation, light weight, low cost and large-area flexible fabrication, and have attracted much attention in recent years. Although the power conversion efficiencies have exceeded 10%, the inferior device stability still remains a great challenge. In this review, we summarize the factors limiting the stability of OSCs, such as metastable morphology, diffusion of electrodes and buffer layers, oxygen and water, irradiation, heating and mechanical stress, and survey recent progress in strategies to increase the stability of OSCs, such as material design, device engineering of active layers, employing inverted geometry, optimizing buffer layers, using stable electrodes and encapsulation. Some research areas of device stability that may deserve further attention are also discussed to help readers understand the challenges and opportunities in achieving high efficiency and high stability of OSCs towards future industrial manufacture.