a-Si:H Photo Diode With Variable Spectral Sensitivity

1996 ◽  
Vol 420 ◽  
Author(s):  
Peter Rieve ◽  
Jürgen Giehl ◽  
Qi Zhu ◽  
Markus Böhm
Keyword(s):  
Thin Film ◽  
Spectral Sensitivity ◽  
Correction Algorithm ◽  
Device Structure ◽  
Band Gap Engineering ◽  
Photo Diode ◽  
Color Separation ◽  
Linearly Independent ◽  
Wide Range ◽  
Color Detection

AbstractA novel two terminal thin film photo diode for color detection has been developed. The device structure which is based on standard amorphous silicon nipin multilayers exhibits three or even more linearly independent spectral sensitivity peaks and provides linearity over a wide range of illumination levels. Band gap engineering and electric field tailoring allow a precise voltage controlled shift of the collection region of photo generated carriers. The steady-state as well as the transient device characteristics have been studied in detail. Emphasis was put on optimization of the spectral sensitivity of the color diodes. Furthermore, an electronic color correction algorithm is presented which results in an improved color separation.

Amorphous Photodiode with an Intermediate Contact for Improved Color Separation

2011 ◽  
Vol 1305 ◽  
Author(s):  
Krystian Watty ◽  
Andreas Bablich ◽  
Konstantin Seibel ◽  
Christian Merfort ◽  
Markus Boehm
Keyword(s):  
Spectral Sensitivity ◽  
Crystalline Silicon ◽  
Low Cost ◽  
Spectral Response ◽  
High Vacuum ◽  
Color Reproduction ◽  
Device Structure ◽  
External Bias ◽  
Color Separation ◽  
Color Filters

ABSTRACTMost of actual photonic devices being sensitive in the visible (VIS) spectrum are based on crystalline silicon (x-Si). The production of x-Si requires an expensive high temperature process. The color reproduction with x-Si diodes additionally requires an integration of color filters [1] to realize a shift in spectral sensitivity. This work presents an amorphous silicon (a-Si:H) photodiode with an intermediate contact for color separation without color filters. Such detectors can be produced in a low cost and low temperature PECVD process, which allows their direct deposition on a custom specific ASIC [2]. Another advantage of a-Si:H is the up to 10 times higher light absorption compared to that of x-Si in the VIS spectrum [3]. The device consists of a metal (Cr) cathode, an amorphous NIP diode structure and a TCO (Al doped ZnO) anode. The I-layer includes an interior TCO contact buried between two P-layers. The thickness of this TCO layer is about 200 nm; the P-layers have a thickness of about 10 nm. The chromium cathode is sputtered on a glass substrate in a PVD process. The amorphous layers are deposited in a multi-chamber PECVD line; the buried and top TCO contacts are sputtered in the same line continuously under high-vacuum conditions. In a first photolithography step the top anode is patterned while the buried anode is uncovered. Afterwards, the diode must be patterned again, resulting in a final Cr, NIP-a-Si:H, TCO, PIP-a-Si:H and TCO multi-layer stack.The spectral sensitivity of a common NIP diode can be shifted by external bias voltages. The spectral sensitivity at higher negative voltages overlays those of that at lower voltages and additionally shifts to longer wavelengths. The color reproduction is difficult; it can be improved by reducing the overlap of the spectral sensitivity [4]. The spectral response of the diodes presented in this work also can be shifted by the bias voltage. Furthermore, it can be split by substituting the disclosed anodes. The spectral response, using the cathode and top anode has a maximum at short wavelengths. If the diode between the interior anode and the cathode is used, the spectral sensitivity for longer wavelengths increases. Shorter wavelengths are blocked by the top part of the diode; it works like a filter. The presented device structure offers good prospects to improve color separation compared to currently existing detectors by using an additional intermediate contact.

The Path Towards Woven Thin-film Transistors

2010 ◽  
Vol 1256 ◽  
Author(s):  
Kunigunde Cherenack ◽  
Gerhard Tröster
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Atomic Layer ◽  
Oxide Thin Film ◽  
Maximum Temperature ◽  
Medical Monitoring ◽  
Electronic Textiles ◽  
Large Area ◽  
Device Structure ◽  
Wide Range

AbstractElectronic textiles (or e-textiles) have a wide range of potential applications in wearable computing and large-area applications, including medical monitoring, assistance to the disabled, and distributed sensor networks. We aim to integrate thin-film electronics directly into clothing during the weaving process. First, thin-film devices are fabricated on plastic substrates. Individual devices are separated by cutting the substrate into stripes which can then be woven into a textile. Devices on stripes need to survive high applied bending strains during weaving. As a first building block, we used atomic layer deposition (ALD) at a maximum temperature of 150oC to fabricate bottom-gate zinc-oxide thin-film transistors (TFTs) with a 25nm-thick Al2O3 gate dielectric, and a 15nm-thick ZnO semiconducting layer on 50μm-thick Kapton E substrates. These TFTs had average mobilities of 12cm2/Vs, threshold voltages around 1V and subthreshold slopes around 250mV/decade. However, after applying a tensile bending diameter of 1cm to the TFTs, ~80% of TFTs fail due to cracking of the brittle device layers. We studied causes of failure and investigated patterning holes in the brittle layers to prevent crack propagation though the channel. This reduced TFT failure to ~45% under the same applied bending conditions. In this paper, we will discuss failure mechanisms in our standard TFT structure when high tensile bending strains are applied and how the device structure was adjusted to decrease TFT failure.

Wide range modulation of synaptic weight in thin-film transistors with hafnium oxide gate insulator and indium-zinc oxide channel layer for artificial synapse application

Nanoscale ◽  
2021 ◽  
Author(s):  
Keonwon Beom ◽  
Jimin Han ◽  
Hyun-Mi Kim ◽  
Tae-Sik Yoon
Keyword(s):  
Thin Film ◽  
Zinc Oxide ◽  
Thin Film Transistors ◽  
Hafnium Oxide ◽  
Synaptic Weight ◽  
Drain Current ◽  
Gate Insulator ◽  
Channel Layer ◽  
Indium Zinc Oxide ◽  
Wide Range

Wide range synaptic weight modulation with a tunable drain current was demonstrated in thin-film transistors (TFTs) with a hafnium oxide (HfO2−x) gate insulator and an indium-zinc oxide (IZO) channel layer...

Plasticity contributions to interface adhesion in thin-film interconnect structures

2000 ◽  
Vol 15 (12) ◽  
pp. 2758-2769 ◽  
Author(s):  
Michael Lane ◽  
Reinhold H. Dauskardt ◽  
Anna Vainchtein ◽  
Huajian Gao
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Fracture Energy ◽  
Fracture Resistance ◽  
Work Of Adhesion ◽  
Interface Fracture ◽  
Cohesive Stress ◽  
Wide Range ◽  
Macroscopic Fracture ◽  
Metal Layers

The effects of plasticity in thin copper layers on the interface fracture resistance in thin-film interconnect structures were explored using experiments and multiscale simulations. Particular attention was given to the relationship between the intrinsic work of adhesion, Go, and the measured macroscopic fracture energy, Gc. Specifically, the TaN/SiO2 interface fracture energy was measured in thin-film Cu/TaN/SiO2 structures in which the Cu layer was varied over a wide range of thickness. A continuum/FEM model with cohesive surface elements was employed to calculate the macroscopic fracture energy of the layered structure. Published yield properties together with a plastic flow model for the metal layers were used to predict the plasticity contribution to interface fracture resistance where the film thickness (0.25–2.5 μm) dominated deformation behavior. For thicker metal layers, a transition region was identified in which the plastic deformation and associated plastic energy contributions to Gc were no longer dominated by the film thickness. The effects of other salient interface parameters including peak cohesive stress and Go are explored.

scholarly journals Prediction of Co and Ru Nanocluster Morphology on 2D MoS2 from Interaction Energies

2021 ◽  
Author(s):  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Thin Film ◽  
Density Functional ◽  
Bulk Material ◽  
Single Layer ◽  
Metal Substrate ◽  
Single Atom ◽  
Metal Interaction ◽  
Wide Range ◽  
Metal Metal ◽  
Sulphur Vacancy

Layered materials, such as \ce{MoS2}, have a wide range of potential applications due to the properties of a single layer which often differ from the bulk material. They are of particular interest as ultra-thin diffusion barriers in semi-conductor device interconnects and as supports for low dimensional metal catalysts. Understanding the interaction between metals and the \ce{MoS2} monolayer is of great importance when selecting systems for specific applications. In previous studies the focus has been largely on the strength of the interaction between a single atom or a nanoparticle of a range of metals, which has created a significant knowledge gap in understanding thin film nucleation on 2D materials. In this paper, we present a density functional theory (DFT) study of the adsorption of small Co and Ru structures, with up to four atoms, on a monolayer of \ce{MoS2}. We explore how the metal-substrate and metal-metal interactions contribute to the stability of metal clusters on \ce{MoS2}, and how these interactions change in the presence of a sulphur vacancy, to develop insight to allow prediction of thin film morphology. The strength of interaction between the metals and \ce{MoS2} is in the order Co > Ru. The competition between metal-substrate and metal-metal interaction allows us to conclude that 2D structures should be preferred for Co on \ce{MoS2}, while Ru prefers 3D structures on \ce{MoS2}. However, the presence of a sulphur vacancy decreases the metal-metal interaction, indicating that with controlled surface modification 2D Ru structures could be achieved. Based on this understanding, we propose Co on \ce{MoS2} as a suitable candidate for advanced interconnects, while Ru on \ce{MoS2} is more suited to catalysis applications.

40 Years Trajectory of Amorphous Semiconductor Research

2000 ◽  
Vol 609 ◽  
Author(s):  
Yoshihiro Hamakawa
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Energy Gap ◽  
Early Period ◽  
Basic Research ◽  
Amorphous Semiconductor ◽  
Film Deposition ◽  
Terrestrial Environment ◽  
Heterojunction Solar Cells ◽  
Wide Range

ABSTRACTA review is given on a research trajectory of amorphous and microcrystalline semiconductors and their device applications proceeded since 1970. A brief explanation on the motivation to start amorphous semiconductor research is given to produce a new kind of synthetic semiconductor having continuous energy gap controllability with valency electron controllability through our experience of modulation spectroscopy in semiconductors.The first material we have challenged is Si-As-Te chalcogenide semiconductor which has a very wide vitreous region in Gibb's Triangle. A series of systematic experiments has been carried out in the terrestrial environment since 1971, and also within the TT-500A rocket experiment in 1980, and the Spacelab. J experiments FMPT (First Material Processing Test) project in 1992. The second material is hydrogenated amorphous silicon (a-Si:H) and its alloys started in 1976 just after the Garmisch Partenkirchen ICALS-6. With some basic research on the a-Si:H film deposition technology and film quality improvement, our continuous effort to improve the efficiency bore the tandem type solar cells in 1979, and also new products of a-SiC:H and a-SiGe:H in the early period of 1980s are described. These innovative device structures and materials have bloomed in the middle of 1980s in R & D phase such as a-SiC/a-Si heterojunction solar cells, a-Si/a-SiGe and also a-Si/poly-Si tandem type solar cells, and industrialized in recent few years. New kind of trials on full-color thin film light emitting devices has also been recently initiated with wide range of band gap controllability of a-SiC:H.The third material is microcrystalline silicon (µc-Si) and their alloys which gathers a tremendous R & D effort as a promised candidate for the bottom cell of the a-Si/µc-Si tandem solar cells aimed for the all-round plasma CVD process for the next age thin film photovoltaic devices. In the final part of presentation, a brief discussion will be given on a technological evolution from “bulk crystalline age” to “multilayered thin film age” in the semiconductor optoelectronics toward 21 century.

Electrochemical Pulsing Deposition of CTZS (Optical and Structural properties) Solar Energy Applications

2018 ◽  
Vol MA2018-01 (31) ◽  
pp. 1927-1927
Author(s):  
Mahfouz Ali Saeed
Keyword(s):  
Thin Film ◽  
Supporting Electrolyte ◽  
Rotating Disk ◽  
Xrd Analysis ◽  
Atomic Ratio ◽  
Rotating Disk Electrode ◽  
Energy Applications ◽  
Behavior Study ◽  
Wide Range ◽  
Steady State Current

Cu2(ZnSn)(S)4 (CTZS) has number of advantages over other solar this film such as CuInGaSe2 (CIGS) due to its higher band gap. Generating such thin film layers by electrochemical methods is particularly attractive because the lower generating budget and the higher throughput. According to literature it is default with many challenges to produce CTZS from electrodeposition methods due to wide range of standard potential of each elements of CTZS 1-4. Sulfur atomic ratio is about 50% of CTZS alloy which add more complexity to electrochemical processing. We introduce in this work electropulsing techniques on order to electroplate at transient current instead of steady state current. Electrolyte composition was similar to dilute concentration from the previous work which is is considerably more dilute in comparison to conventional electrolytes used in the literature1-4. The bath composition is: 0.0042 M CuSO4, 0.0031 M ZnSO4, 0.035 M SnCl2, 0.005 M Na2S2O3, and 0.045 M Na2S2O3. PHydrion is used to buffer the electrolyte to pH=2, and supporting electrolyte is 0.6 M LiCl. Experiments was conducted at a rotating disk electrode which offers measureable characterization of the rotating flow at room temperature. Electrochemical pulsing current behavior study at different off and on time and current in Fig. 1 and 2. The effects of pulsing time and current density on the CTZS thin film adhesion and atomic composition are discussed. The annealing was carried out on tube furnace under sulfur element atmosphere with no extra material addition. The amount of sulfur on the absorber layer was optimized. The alloy composition was examined using Energy-dispersive X-ray spectroscopy technique (EDS) Fig. 2. XRD analysis method used to characterized CTZS thickness and crystallography. Figure 1

Modelling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications

2020 ◽  
Author(s):  
K. Singh ◽  
M. Sharabi ◽  
R. Jefferson-Loveday ◽  
S. Ambrose ◽  
C. Eastwick ◽  
...  
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
Operating Conditions ◽  
Film Model ◽  
Thin Film Model ◽  
Wide Range ◽  
Aero Engine

Abstract In the case of aero-engine, thin lubricating film servers dual purpose of lubrication and cooling. Prediction of dry patches or lubricant starved region in bearing or bearing chambers are required for safe operation of these components. In the present work thin liquid film flow is numerically investigated using the framework of the Eulerian thin film model (ETFM) for conditions which exhibit partial wetting phenomenon. This model includes a parameter that requires adjustment to account for the dynamic contact angle. Two different experimental data sets have been used for comparisons against simulations, which cover a wide range of operating conditions including varying the flow rate, inclination angle, contact angle, and liquid-gas surface tension coefficient. A new expression for the model parameter has been proposed and calibrated based on the simulated cases. This is employed to predict film thickness on a bearing chamber which is subjected to a complex multiphase flow. From this study, it is observed that the proposed approach shows good quantitative comparisons of the film thickness of flow down an inclined plate and for the representative bearing chamber. A comparison of model predictions with and without wetting and drying capabilities is also presented on the bearing chamber for shaft speed in the range of 2,500 RPM to 10,000 RPM and flow rate in the range of 0.5 liter per minute (LPM) to 2.5 LPM.

Sign in / Sign up

Export Citation Format

Share Document