In this work we present the investigations aimed at the optimization of the technology of Reactive Ion Etching in sulfur hexafluoride (SF6) plasma of silicon, which is necessary during fabrication of TFET according to the original concept of the device designed at Institute of Microelectronics and Optoelectronics (IMiO) of Warsaw University of Technology (WUT) laboratory. We have performed a two-stage optimization of RIE process’ parameters in order to obtain a controllable process characterized by good selectivity and anisotropy. Presented in this study findings have shown that the SF6 flow most significantly influence onto the RIE process’ results. Selected and optimized processing step will be used in the course of the fabrication of TFET devices, in future.
In this work, we report the technology of infrared photodetectors based on graphene layers (GLs). In the course of this work the new set of photolithography masks was especially designed to fabricate test structures. The new masks-set contains a matrix of different types of photodetector structures with varied active area dimensions, as well as additional module for characterization of electro-physical parameters of graphene and graphene-based devices. After careful optimization of consecutive technological steps, test structures were fabricated. First results of electrical characterization of obtained graphene-based photodetectors demonstrated that the developed technology was successful, however, further detailed optical characterization towards sensing parameters and potential applications in infrared detectors is necessary.
In this work, we present the design of the technology and fabrication of TFTs with amorphous IGZO semiconductor and high-k gate dielectric layer in the form of hafnium oxide (HfOx). In the course of this work, the IGZO fabrication was optimized by means of Taguchi orthogonal tables approach in order to obtain an active semiconductor with reasonable high concentration of charge carriers, low roughness and relatively high mobility. The obtained Thin-Film Transistors can be characterized by very good electrical parameters, i.e., the effective mobility (μeff ≈ 12.8 cm2V-1s-1) significantly higher than that for a-Si TFTs (μeff ≈ 1 cm2V-1s-1). However, the value of sub-threshold swing (i.e., 640 mV/dec) points that the interfacial properties of IGZO/HfOx stack is characterized by high value of interface states density (Dit) which, in turn, demands further optimization for future applications of the demonstrated TFT structures.
This paper discusses the influence of coating long-period gratings with a silicon nitride thin overlay on the grating’s
spectral response. The overlays have been obtained with a radio frequency plasma enhanced chemical vapor deposition
method. During the experiment, the structures were positioned on various heights over the electrode using specially
developed sample holder. The results of the experiment show that the investigated long period grating structures have
increased their sensitivity to variations of external medium refractive index in the range of nD=1.33 to 1.43 RIU. The
relation between the height at which the long period grating was placed over the electrode and the deposited overlay
symmetry is discussed. The highest sensitivity of 2080 nm/RIU has been observed for the grating placed at the highest
positions of the holder out of the examined range of 3 to 8 mm over the electrode. This overlay also shows the highest
symmetry around the fiber.
Reactive magnetron sputtering technique using O2/Ar gas mixture was used to deposit Gd2O3 layers. Following
metallization process of Al allowed to create MIS structures, which electrical parameters (κ, Dit, UFB, ρ, etc.) were
measured using high frequency C-V equipment. Created layers exhibit high permittivity (κ≈12) at 100kHz. I-V
measurements point out on maximum electric break down field Ebr≈0.4 MV/cm and maximum break down voltage Ubr ≈
16V. Layers were morphologically tested using AFM technique (Ra ≈ 0.5÷2nm). Layer thicknesses as well as refractive
indexes (RI ≈ 1.50÷2.05) were estimated using ellipsometry measurements.
In this paper, a method of designing a Raman laser structures with Bragg mirrors used to coupling pump signal, forming
a resonator and lead-out laser signal outside is presented. The Raman laser is SOI waveguide structure (such as "rib,"
i.e. ridge waveguide) with built-in reverse biased p-i-n diode, wherein the optical gain is generated by stimulated Raman
effect in the waveguide. Our way of designing is based on the effective refractive index method. Design of Raman laser
with Bragg mirrors consists of two main stages: the first step is the choice of the optimum size and shape of the rib
waveguide; the second step is the selection of Bragg gratings parameters. Our method of designing such Raman laser
structures is a design tool, which uses analytical dependences and allows specifying optimal geometric parameters of one
mode laser.
This study described a novel and original method of ultra-shallow fluorine and nitrogen implantation from radio
frequency (RF = 13,56MHz) CF4 and NH3 plasmas, performed in classical RIE / PECVD reactors. The performed
experiments indicate that ultra-shallow implantation of high concentration of fluorine and nitrogen ions by using r.f.
plasma reactors (PECVD ad RIE) is feasible. It is also possible to control the implantation process parameters, ie
implantation depth and maximum concentration, by controlling the parameters of the plasma processes.
Electrical characterization of MOS structures with HfO2 layer as a gate dielectric, shows that samples implanted with
nitrogen, have the best insulating properties, better even the reference sample. Samples prepared by fluorine
implantation, exhibit much worse I-V behavior for low, medium and high electric fields, than all samples studied in this
article. This samples exhibit the highest leakage currents, too.
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