Optical properties of photoconductor using crystalline selenium

2014 ◽  
Vol 92 (7/8) ◽  
pp. 645-647 ◽  
Author(s):  
Shigeyuki Imura ◽  
Kenji Kikuchi ◽  
Kazunori Miyakawa ◽  
Misao Kubota
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Metal Electrode ◽  
Image Sensors ◽  
High Quantum Efficiency ◽  
Suitable Material ◽  
Light Region ◽  
Highly Sensitive ◽  
Photosensitive Layer ◽  
High Absorption Coefficient

Recently, there has been an increased need for highly sensitive solid-state imaging devices to develop high-resolution and high-speed image sensors. Crystalline selenium is a suitable material for a photosensitive layer because of its high absorption coefficient in the visible light region. In our experiment with an image pick-up tube using crystalline selenium as a photosensitive layer, a high-resolution image was obtained for the first time. In addition, test sandwich cells have been fabricated to demonstrate a large photocurrent multiplication phenomenon with very high quantum efficiency greatly exceeding unity as a result of injection carriers from an external electrode caused by a high electric field at the interface between the crystalline selenium and the metal electrode.

Electrical Properties of Photoconductor Using Ga2O3/CuGaSe2 Heterojunction

2013 ◽  
Vol 1538 ◽  
pp. 391-395
Author(s):  
Kenji Kikuchi ◽  
Shigeyuki Imura ◽  
Kazunori Miyakawa ◽  
Misao Kubota ◽  
Eiji Ohta
Keyword(s):  
Visible Light ◽  
Dark Current ◽  
Carrier Density ◽  
Depletion Region ◽  
Image Sensors ◽  
High Quantum Efficiency ◽  
Light Region ◽  
Cigs Thin Film ◽  
Hole Blocking Layer ◽  
High Absorption Coefficient

ABSTRACTThe feasibility of using a photoconductor with a Ga2O3/CuGaSe2 heterojunction for visible light sensors was investigated. CIGS chalcopyrite semiconductors have both a high absorption coefficient and high quantum efficiency. However, their dark current is too high for image sensors. In this study, we applied gallium oxide (Ga2O3) as a hole-blocking layer for CIGS thin film to reduce the dark current. Experimental results showed that the dark current was drastically reduced, and an avalanche multiplication phenomenon was observed at an applied voltage of over 6 V. However, this structure had sensitivity only in the ultraviolet light region because its depletion region was almost completely spread in the Ga2O3 layer since the carrier density of the Ga2O3 layer was much lower than that of the CIGS layer. These results indicate that the Ga2O3/CuGaSe2 heterojunction has potential for use in visible light sensors but that we also need to increase the carrier density of the Ga2O3 layer to shift the depletion region to the CIGS film.

Electrical Properties of Ga2O3:Sn/CIGS Hetero-junction

2014 ◽  
Vol 1603 ◽  
Author(s):  
Kenji Kikuchi ◽  
Shigeyuki Imura ◽  
Kazunori Miyakawa ◽  
Misao Kubota ◽  
Eiji Ohta
Keyword(s):  
Thin Film ◽  
Visible Light ◽  
Dark Current ◽  
Carrier Density ◽  
High Speed ◽  
Depletion Region ◽  
Image Sensors ◽  
Frame Rate ◽  
Semiconductor Layer ◽  
High Quantum Efficiency

ABSTRACTThere is an increased need for highly sensitive imaging devices to develop high resolution and high speed image sensors. Incident light intensity per pixel of image sensors is getting lower because the pixel resolution and frame rate of image sensors are becoming higher. We investigated the feasibility of using a photoconductor with tin-doped gallium oxide (Ga2O3:Sn)/Cu(In,Ga)Se2 (CIGS) hetero-junction for visible light image sensors. CIGS chalcopyrite thin films have great potential for improving the sensitivity of image sensors and CIGS chalcopyrite semiconductors have both a high absorption coefficient and high quantum efficiency. Moreover, the band gap can be adjusted for visible light. We applied Ga2O3 as an n-type semiconductor layer and a hole-blocking layer to CIGS thin film to reduce the dark current. The experimental results revealed that dark current was drastically reduced due to the application of Ga2O3 thin film, and an avalanche multiplication phenomenon was observed at an applied voltage of over 6 V. However, non-doped Ga2O3/CIGS hetero-junction only had sensitivity in the ultraviolet light region because their depletion region was almost completely spread throughout the Ga2O3 layer due to the low carrier density of the Ga2O3 layer. Therefore, we used Ga2O3:Sn for the n-type layer to increase carrier density. As a result, the depletion region shifted to the CIGS film and the cells had sensitivity in all visible regions. These results indicate that Ga2O3:Sn/CIGS hetero-junction are feasible for visible light photoconductors.

scholarly journals 4+1-transistor pixel architecture for high-speed, high-resolution CMOS image sensors

2011 ◽  
Vol 47 (22) ◽  
pp. 1221 ◽  
Author(s):  
A. Xhakoni ◽  
D. San Segundo Bello ◽  
P. De Wit ◽  
G. Gielen
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Image Sensors ◽  
Cmos Image Sensors

Electrical Probing and Surface Imaging of Deep Sub-Micron Integrated Circuits

1999 ◽  
Author(s):  
Kenneth Krieg ◽  
Richard Qi ◽  
Douglas Thomson ◽  
Greg Bridges
Keyword(s):  
High Resolution ◽  
Integrated Circuits ◽  
Real Time ◽  
High Speed ◽  
Time Signal ◽  
Surface Imaging ◽  
Atomic Force ◽  
Submicron Structures ◽  
High Resolution Images ◽  
Capacitive Loading

Abstract A contact probing system for surface imaging and real-time signal measurement of deep sub-micron integrated circuits is discussed. The probe fits on a standard probe-station and utilizes a conductive atomic force microscope tip to rapidly measure the surface topography and acquire real-time highfrequency signals from features as small as 0.18 micron. The micromachined probe structure minimizes parasitic coupling and the probe achieves a bandwidth greater than 3 GHz, with a capacitive loading of less than 120 fF. High-resolution images of submicron structures and waveforms acquired from high-speed devices are presented.

scholarly journals PIK3CA Hotspot Mutation Scanning by a Novel and Highly Sensitive High-Resolution Small Amplicon Melting Analysis Method

2010 ◽  
Vol 12 (5) ◽  
pp. 697-704 ◽  
Author(s):  
Panagiotis A. Vorkas ◽  
Nikoleta Poumpouridou ◽  
Sophia Agelaki ◽  
Christos Kroupis ◽  
Vassilis Georgoulias ◽  
...  
Keyword(s):  
High Resolution ◽  
Analysis Method ◽  
Mutation Scanning ◽  
Highly Sensitive ◽  
Melting Analysis ◽  
Hotspot Mutation
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