Analytical Threshold Voltage Model Considering Quantum Size Effects for Nanocrystalline Silicon Thin Film Transistors

This paper presents an analytical model calculating the threshold voltage in nanocrystalline silicon (nc-Si) thin film transistors by considering a granular morphology of silicon nanocrystallites forming the channel and using the two-dimensional the Poisson equation. The numerical calculations demonstrate that, according to the quantum size effects on both dielectric constant and band gap, the threshold voltage values are strongly related to the silicon crystallites structure. To justify the validity of our model suitable for implementation in circuit simulators such as SPICE, the simulation results obtained are compared with the available research data and they shows a satisfactory match, thus, demonstrating the validity of our model

Compact Modeling for Submicron Fully Depleted SOI MOSFET's

In this paper, we have developed a novel compact charge-conservative model for fully depleted silicon-on-insulator MOSFETs and implemented it in SPICE3. Our model is valid for the DC, small-signal and large-signal simulations over a wide range of temperature. Simulations made using the model, following parameter extraction, are validated by comparison with experimental data

STUDY OF ELECTRICAL AND STRUCTURAL PROPERTIES OF BORON DOPED POLYSILICON FILMS WITH A LOW NITROGEN CONTENT

International audienceIn this work we propose, the study of nitrogen doped Silicon films for an application as a poly-Si gate material for metal-oxide-semiconductor devices. Nitrogen doped silicon films have been deposited at amorphous phase by low-pressure chemical vapor deposition (LPCVD) from disilane Si2H6 and ammonia NH3 at low temperature (480∘C). The films with varied nitrogen contents have been boron implanted, and annealed at several annealing conditions. The influence of the annealing conditions, the nitrogen tenor and the boron dose on the electrical and the structural properties of films are investigated and correlated. Results show that the conductivity is maximal (σ ∼ 102 (Ω ⋅ cm)−1) for higher annealing temperature, a nitrogen content less than 2% and a strong boron dose. These results indicate that under these optimal conditions, although some nitrogen contents is present in the films, these latter have a conducting behavior. The crystallization of films was found to depend principally on the nitrogen tenor. A quasi-totally crystallization was observed for a nitrogen tenor inferior or equal to 2% and for an annealing temperature of 1100∘C during 120 min. This result is in good agreement with the greatest value of the conductivity obtained under the same conditions

Contribution a l'etude des proprietes de transport ionique d'electolytes polymeres : les polyethers-sels de lithium

SIGLECNRS TD 15427 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Formation of silicon nanocrystals by thermal annealing of low-pressure chemical-vapor deposited amorphous SiNx (x=0.16) thin films

International audienceSilicon nanocrystals have been produced by thermal annealing of SiNx thin film obtained by low pressure chemical vapor deposition using a mixture between disilane and ammonia. Morphological, structural, and photoluminescence properties of the thin film were investigated using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and photoluminescence spectroscopy. The results revealed a high crystallinity of film with a crystalline volume fraction exceeded 70 %, and a dominance of silicon nanocrystallites having the sizes within the range 2.5-5 nm and density ~1.98.10 12 /cm 2. The PL peaks consist of nanocrystalline silicon and amorphous silicon. The luminescence from the silicon nanocrystals was dominant

Study of Silicon Nanocrystals Formation in Annealed Amorphous In Situ Nitrogen Doped Silicon Thin Films Obtained by Low Pressure Chemical Vapor Deposition

In this work, we investigate the formation of silicon nanocrystals in annealed low pressure chemical vapor deposition in situ nitrogen doped silicon thin films $(SiN_x)$ obtained at low temperature (465°C) by using a mixture of disilane $(Si_2H_6)$ and ammonia $(NH_3)$. Results show that nitrogen content in films plays an important role in defining the obtained films morphology in terms of crystallites sizes and their distribution. Indeed, according to the nitrogen content introduced in films, the crystalline state of films varies from a submicron crystalline structure to a nanocrystalline structure. An average silicon nanocrystalline size of 10 nm was obtained for film with x = 0.07 nitrogen content, annealed under a temperature of 850C during 2 h

Structural, morphological and electrical properties of La1-xSrxAlO3-delta(x=0, 0.1, 0.15) synthesized by the Pechini method

La1-xSrxAlO3-delta (x = 0, 0.1, 0.15) fine particles were prepared by the Pechini process using citric acid and ethylene glycol at low temperature 900 degrees C. The powders were studied by several physical characterization techniques. The FTIR spectrum of the resin treated at 200 degrees C revealed the formation of a metalorganic complex and a polymerized form of ethylene glycol. XRD spectra of the samples, calcined at 900 degrees C, illustrated a single phase LaAlO3. However, La0.9Sr0.1AlO3-delta and La0.85Sr0.15AlO3-delta powders mainly consist of a deficient hexagonal perovskite phase with a small amount of a second phase (LaSrAl3O7). Ionic conductivities of these materials were studied by impedance spectroscopy in the range of 100-700 degrees C in air

Experimental and theoretical investigation of the graphene ribbons nonlinear electrical behavior

In this study, we experimentally investigate the carrier transport nonlinear behavior in back-gated graphene transistors. The graphene ribbons are monolayer graphene formed by chemical vapor deposition process and transferred on SiO2/Si substrate. The electrical characterization with a micro prober setup of hundreds of devices has been performed under vaccuum and for a temperature ranging from 300K down to 77K. We can distinguish two categories of electrical behavior, respectively, linear and nonlinear electrical output characteristics. The linear behavior excludes the impact of the Schottky barrier between both metallic source and drain contacts and graphene. The study is focused on the impact of the technological parameters on the electrical characteristics of back-gated graphene transistors. Equivalent circuit simulations show that, first, the output characteristics slopes are strongly influenced by the doping concentration value. Second, during the fabrication process the graphene is doped by its environment, which makes the doping parameter experimentally difficult to control. The in situ Raman characterization along the ribbons area highlights interesting results for 2D peaks shift and intensity. The Raman shift variation corresponding to the position of the 2D peak between all measured spectra extends from 2697 cm-1 to 2700 cm-1 for devices exhibiting a linear behavior. While, for the devices exhibiting a nonlinear behavior, the variation range is more important, from 2686 cm-1 to 2704 cm-1. These results reveal that the doping level between two regions within the ribbon area is clearly different. Furthermore, the Raman mapping characterization shows a high variability of the 2D peak intensity. The extraction of the ribbons doping profile for both the minimum doping corresponding to the charge neutrality point and the doping issued from the gate oxide are in agreement with these results. Indeed, the electrical behavior appears strongly related to the doping concentration and distribution along the graphene layer