Articles you may be interested inActive-matrix Spindt-type field emitter array with faster response time for image sensor with high-gain avalanche rushing amorphous photoconductor target J. Vac. Sci. Technol. B 33, 012205 (2015); 10.1116/1.4906103 Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency xray imaging properties of the solid-state SHARP sensor structure Med. Phys. 39, 7102 (2012); 10.1118/1.4760989 Electrostatic focusing Spindt-type field emitter array for an image sensor with a high-gain avalanche rushing amorphous photoconductor target J. Vac. Sci. Technol. B 29, 04E104 (2011); 10.1116/1.3610960 640 × 480 pixel active-matrix Spindt-type field emitter array image sensor with high-gain avalanche rushing amorphous photoconductor target J. Vac. Sci. Technol. B 28, 96 (2010); 10.1116/1.3272732 256×192 pixel field emitter array image sensor with high-gain avalanche rushing amorphous photoconductor target J.A 50ϫ 50 m pixel field emitter array image sensor with a highly sensitive avalanche-mode photoconductive target and a scanning electron focusing system consisting of permanent magnets were fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors for high-definition television cameras. The experimental results revealed that the magnetic focusing conditions of the prototype sensor were in accordance with those estimated from the simulation, and the prototype sensor could obtain both enough resolution for its pixel size and high sensitivity by focusing the electrons emitted from the field emitter array onto the highly sensitive photoconductive target.
Articles you may be interested inActive-matrix Spindt-type field emitter array with faster response time for image sensor with high-gain avalanche rushing amorphous photoconductor target J. Vac. Sci. Technol. B 33, 012205 (2015); 10.1116/1.4906103 Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency xray imaging properties of the solid-state SHARP sensor structure Med. Phys. 39, 7102 (2012); 10.1118/1.4760989 Electrostatic focusing Spindt-type field emitter array for an image sensor with a high-gain avalanche rushing amorphous photoconductor target J. Vac. Sci. Technol. B 29, 04E104 (2011); 10.1116/1.3610960 640 × 480 pixel active-matrix Spindt-type field emitter array image sensor with high-gain avalanche rushing amorphous photoconductor target J. Vac. Sci. Technol. B 28, 96 (2010); 10.1116/1.327273250 × 50 μ m pixel magnetic focus field emitter array image sensor with high-gain avalanche rushing amorphous photoconductor target A 256ϫ192 pixel field emitter array ͑FEA͒ image sensor with a highly sensitive high-gain avalanche rushing amorphous photoconductor ͑HARP͒ target was fabricated and tested as a step toward the development of a practical image sensor for ultrahigh sensitivity and ultrahigh-definition compact TV cameras. The experimental results showed that the prototype had an adequate resolution corresponding to the spot size of the scanning electrons on the HARP target which was estimated by the simulation. The prototype also had a wide dynamic range and high sensitivity, demonstrating its potential as a next generation practical image sensor and offering new application of FEAs.
In a new application of field emitter arrays (FEAs), a unique, ultrahigh-sensitivity, flat image sensor that consists of an FEA and a avalanche-mode photoconductive target is proposed.We have been working to develop highly sensitive camera tubes with a high-gain avalanche rushing amorphous photoconductor (HARP) target. Although our latest HARP tube is about 100 times as sensitive as a conventional solid-state image sensor, it suffers from drawbacks related to its length (about 100 mm) and power consumption. To overcome these problems and develop a next-generation, ultrahigh sensitivity, flat image sensor, we have developed an FEA image sensor.The configuration and operating principle of an FEA flat image sensor are shown in Fig. 1. The sensor consists of an FEA, a mesh electrode, and a HARP target, facing each other in close proximity. The FEA acts as an electron source and the mesh electrode accelerates electrons emitted from the field emitters and suppress their divergence. The HARP target converts incident light to electric charges and multiplies them through an intemal avalanche multiplication effect. A video signal is obtained, pixel-by -pixel, through the recombination of the two-dimensional charge (hole) pattem accumulated on the HARP target and the electrons emitted from the FEA. Figure 2 shows a prototype FEA image sensor. The prototype is only 10 mm thick and has 128 horizontal and 96 vertical pixels. Light output Spindt-type field emitters (a) Configuration (b) Operating principle Fig. 1 Configuration and operating principle of FEA image sensor with HARP target 0-7803-7256-5/02/$10.00 0 2002 IEEE 63
The recent improvements of complementary metal–oxide–semiconductor (CMOS) image sensors are playing an essential role in emerging high-definition video cameras, which provide viewers with a stronger sensation of reality. However, the devices suffer from decreasing sensitivity due to the shrinkage of pixels. We herein address this problem by introducing a hybrid structure comprising crystalline-selenium (c-Se)-based photoconversion layers and 8 K resolution (7472 × 4320 pixels) CMOS field-effect transistors (FETs) to amplify signals using the avalanche multiplication of photogenerated carriers. Using low-defect-level NiO as an electric field buffer and an electron blocking layer, we confirmed signal amplification by a factor of approximately 1.4 while the dark current remained low at 2.6 nA/cm2 at a reverse bias voltage of 22.6 V. Furthermore, we successfully obtained a brighter image based on the amplified signals without any notable noise degradation.
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