ITO/a-SiNx:H/a-Si:H Photodiode with Enhanced Photosensitivity and Reduced Leakage Current Using Polycrystalline ITO Deposited at Room Temperature

2000 ◽  
Vol 609 ◽  
Author(s):  
S. Tao ◽  
Q. Ma ◽  
D. Striakhilev ◽  
A. Nathan
Keyword(s):  
Leakage Current ◽  
Dark Current ◽  
Room Temperature ◽  
Dynamic Range ◽  
Transport Model ◽  
Measurement Data ◽  
Mis Structure ◽  
Defect States ◽  
Large Area ◽  
Density Of Defect States

ABSTRACTWe report an ITO/a-SiNx:H/a-Si:H MIS photodiode structure based on room temperature deposition of optically transparent polycrystalline ITO for applications in large area optical and x-ray imaging. The photodiode structure exhibits device characteristics with reduced leakage current and enhanced photosensitivity giving rise to a hundred-fold improvement in dynamic range. This notable improvement in performance is believed to be due to the reduced diffusion of oxygen from the ITO to the a-Si:H layer, and thus reducing the density of defect states inside the a-Si:H layer. The behavior of photo and dark current is consistent with an elaborate transport model for the Schottky barrier. The model agrees reasonably well with measurement data for the dark current and provides a consistent picture in terms of the photo current behavior in the MIS structure, where the insulating layer serves to reduce the oxygen diffusion.

Large Area, Full-Color Image Sensors Made with Organic Semiconductors

1999 ◽  
Vol 558 ◽  
Author(s):  
G. Yu ◽  
G. Srdanov ◽  
J. Wang ◽  
A.J. Heeger
Keyword(s):  
Dark Current ◽  
Dynamic Range ◽  
Color Image ◽  
Sensor Arrays ◽  
Blue Color ◽  
Two Dimensional ◽  
Large Area ◽  
Full Color ◽  
Sensing Applications ◽  
Photodiode Arrays

ABSTRACTLarge area polymer photodiode arrays were designed and fabricated for full-color imaging applications. These sensor arrays are of high photosensitivity, low dark current, large dynamic range and fast response time. The red, green and blue color primaries were achieved by coupling a set of color filters with the polymer sensor pixels with broad response covering entire visible spectrum. Image recovery process from the pixel photocurrent data was developed, which is suitable generally to image arrays with power-law light intensity dependence and with finite pixel dark current. Large sensing length photodiode arrays (2.5”5”) were fabricated with pixel densities from 40 to 100 dot-per-inch. They were used as the sensing elements in page size document scanners. Voltage switchable polymer photodetectors were developed. Their photosensitivity can be switched on and off with external bias. These devices can be used as the sensing elements in x-y addressable two-dimensional sensor matrices. The high on/off switching ratio and high photocurrent/dark-current ratio allow such two-dimensional, passive photosensor matrices be used for image sensing applications.

Transport Properties of Amorphous Silicon / Silicon Oxide Heterostructures

1986 ◽  
Vol 70 ◽  
Author(s):  
H. Steemers ◽  
J. Mort ◽  
I. Chen ◽  
F. Jansen ◽  
S. Grammatica ◽  
...  
Keyword(s):  
Glow Discharge ◽  
Amorphous Silicon ◽  
Room Temperature ◽  
Silicon Oxide ◽  
Transport Model ◽  
Electron Lifetime ◽  
Defect States ◽  
Time Resolved ◽  
Oxide Heterostructures ◽  
Silicon Silicon

ABSTRACTThe transport of excess carriers in glow-discharge deposited a-Si:H/insulator heterostructures has been studied by time-of-flight and xerographic discharge techniques. Efficient injection of photocarriers from a-Si:H into, and transport through, relatively thick SiOx:N:H has been achieved. A mobility-lifetime product approaching 18−6 cm2V−1 is found for electrons in SiOx:N:H, and time resolved measurements indicate a room temperature mobility of 5×10−6 cm2v−1s−1 at a field of 2×104 Vcm−1, suggesting an electron lifetime of the order of 8.2 seconds. The results are contrasted with transport measurements on thermally grown SiO2 on Si and a transport model involving hopping through defect states within the gap of SiOx:N:H is discussed.

DETERMINATION OF DENSITY-OF-STATES OF NANOCLUSTER CARBON THIN FILMS MIS STRUCTURE USING CAPACITANCE–VOLTAGE TECHNIQUE

2011 ◽  
Vol 25 (10) ◽  
pp. 763-772 ◽  
Author(s):  
SHOUNAK DE ◽  
JHUMA GOPE ◽  
B. S. SATYANARAYANA ◽  
O. S. PANWAR ◽  
MOHAN RAO
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Mis Structure ◽  
Defect States ◽  
Metal Insulator ◽  
Capacitance Voltage ◽  
Carbon Thin Films ◽  
Density Of Defect States ◽  
Cathodic Arc

Nanocluster carbon thin films (NC) were deposited at room temperature by cathodic arc process. These films were clustered, amorphous and disordered in nature which is verified using Raman spectroscopy. Density of defect states (DOS), which influences electronic and optical properties, were determined from the capacitance–voltage (C–V) characteristic of Al / NC / c - Si metal–insulator–semiconductor (MIS) structure near the Fermi level of undoped samples. Dielectric constant of the films was also estimated using the same technique. The DOS were found to be varying from 5.68 × 1016 to 4.9 × 1019 cm-3. The dielectric constant varied between 2.76 to 11.8.

ELECTRICAL AND PHOTOELECTRICAL PROPERTIES OF A-Ge20Te80-xBix (x = 0, 1.5, 2.5, 5.0) THIN FILMS

2013 ◽  
Vol 22 ◽  
pp. 439-451
Author(s):  
AMBIKA SHARMA ◽  
KUMARI ANSHU ◽  
PREETI YADAV
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Life Time ◽  
Defect States ◽  
Temperature Dependent ◽  
Photoelectrical Properties ◽  
Glassy Alloys ◽  
Localized State ◽  
Evaporation Technique ◽  
Density Of Defect States

Bulk samples of Te-rich Ge20Te80-xBix (x = 0, 1.5, 2.5, 5.0) glassy alloys are prepared by melt quenching technique. The thin films of the bulk samples are deposited by using vacuum evaporation technique for their electrical and photoelectrical measurements. Keithley 6487 picoammeter has been used to study the electrical and photoelectrical characteristics of Ge20Te80-XBix thin films kept in vacuum. Temperature dependent dark and photoconductivity is studied in the temperature range 300-360 K and voltage V = 80V. Photoconductivity with intensity at room temperature follows a power law where power γ lies near to 0.5, suggesting that the recombination is bimolecular in nature. The density of defect states and photosensitivity are found to follow an opposite trend with each other. The differential life time is determined from the rise and decay of photocurrent w.r.t. time. The dispersion parameter and localized state distribution parameter are estimated from decay curves and reported for the studied composition.

Amorphous Silicon Thin Film Transistors and Memory Devices

1985 ◽  
Vol 49 ◽  
Author(s):  
P.G. Lecomber
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Field Effect Transistors ◽  
Memory Devices ◽  
Preparation Technique ◽  
Defect States ◽  
Large Area ◽  
Silicon Thin Film ◽  
Simple Logic ◽  
Density Of Defect States

AbstractThe preparation of amorphous silicon with a low density of defect states by the glow discharge decomposition of silane and the ability to control its electrical conductivity over many orders of magnitude by the addition of phosphine or diborane to the silane, stimulated a worldwide interest in this material and in its possible applications. This paper begins with a description of the preparation technique and a brief review of some of the important properties of the material. The fabrication and characteristics of a-Si thin-film field effect transistors will be described and followed by a discussion of the applications of these devices in large area liquid crystal displays, in simple logic circuits and in addressable image sensors. Finally, the use of a-Si in memory devices will be briefly described.

Transient current in a-Si:H-based MIS photosensors

2008 ◽  
Vol 1066 ◽  
Author(s):  
Miguel Fernandes ◽  
Yuriy Vygranenko ◽  
Manuela Vieira ◽  
Gregory Heiler ◽  
Timothy Tredwell ◽  
...  
Keyword(s):  
Dark Current ◽  
Elevated Temperatures ◽  
Sensor Arrays ◽  
Charge Trapping ◽  
Transient Current ◽  
Mis Structure ◽  
Current Component ◽  
Large Area ◽  
Semiconductor Interface ◽  
X Ray

ABSTRACTLarge-area amorphous silicon (a-Si:H) sensor arrays are widely used for medical x-ray imaging, nondestructive testing and security screening. Most of the commercially available detectors are of the indirect conversion type, in which an x-ray phosphor screen is optically coupled to an array of a-Si:H sensors. The a-Si:H PIN photodiode and the MIS photoelectric converter are two alternative sensing elements used in these detectors. The major advantage of the MIS structure over PIN is fact that this device has the same layer sequence as the a Si:H TFT switch and therefore, they can be fabricated simultaneously resulting in an effective reduction in the lithography mask count. The main disadvantage of the MIS structure is the higher noise level due to transient dark current. The transient dark current originates from traps at the semiconductor-insulator interface and i-layer bulk defects. In this work we analyze the transient current transport in segmented-gate/SiN/a Si:H/n+/ITO structures under different biasing conditions and temperatures. Using a home-made setup the dark current decay was measured within an interval of 1 second in the temperature range from 294 to 353K. It is found that the dark current component associated with charge trapping at the insulator-semiconductor interface can be largely eliminated by adjusting the bias voltage during the refresh period. Under optimized biasing conditions and elevated temperatures the bulk current component becomes dominant.

Temperature Dependence of Leakage Current in Segmented a-Si:H n-i-p Photodiodes

2007 ◽  
Vol 989 ◽  
Author(s):  
Jeff Hsin Chang ◽  
Tsu Chiang Chuang ◽  
Yuri Vygranenko ◽  
Denis Striakhilev ◽  
Kyung Ho Kim ◽  
...  
Keyword(s):  
Leakage Current ◽  
Dark Current ◽  
Reverse Current ◽  
Medical Diagnostics ◽  
Central Component ◽  
Large Area ◽  
Ambient Temperatures ◽  
Hardware Description ◽  
Current Characteristics ◽  
Hydrogenated Amorphous

AbstractHydrogenated amorphous silicon (a-Si:H) n-i-p photodiodes may be used as the pixel sensor element in large-area array imagers for medical diagnostics applications. The dark current level is an important parameter that dictates the performances of these types of pixelated imaging devices. Through measurements performed at different ambient temperatures, the leakage current components of segmented a-Si:H n-i-p photodiodes were extracted and analyzed. It was found that the central component of the reverse current depends exponentially on bias and temperature. The activation energy of this component is independent of bias. The peripheral component of reverse current exhibits linear bias dependence at temperatures up to 50°C, while the contribution of this component diminishes at high temperatures. The dependence of dark current components on bias and temperature could be described by compact analytical equations. The model of forward and reverse dark current characteristics in temperature range was implemented in Verilog-A hardware description language.

Low dark current and high dynamic range a-Si:H MSM photodetector for large area medical imaging

2013 ◽  
Author(s):  
Sina Ghanbarzadeh ◽  
Shiva Abbaszadeh ◽  
Michael Adachi ◽  
Karim S. Karim
Keyword(s):  
Medical Imaging ◽  
Dark Current ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Large Area ◽  
Msm Photodetector ◽  
High Dynamic

Dark Current Spectroscopy Of Metals In Silicon

1996 ◽  
Vol 442 ◽  
Author(s):  
William C. Mccolgin ◽  
James P. Lavine ◽  
Charles V. Stancampiano
Keyword(s):  
Low Temperature ◽  
Leakage Current ◽  
Dark Current ◽  
Room Temperature ◽  
Image Sensors ◽  
Active Iron ◽  
Metal Atoms ◽  
Individual Metal

AbstractDark current spectroscopy (DCS) is used to identify the signature of metals that generate dark or leakage current in silicon image sensors. Individual metal atoms or defects are detected by DCS on a pixel-by-pixel basis. DCS is applied here to show how the number of electrically active iron atoms in a pixel changes with light and with low-temperature anneals. The measurements explore the dissociation and association of iron-boron pairs and the diffusion of iron near room temperature.

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