NEC Develops High Sensitivity Half-THz Image Sensor

NEC announces a new pixel structure for Thz array sensors and improved the Minimum Detectable Power per pixel (MDP) at 0.5 - 0.6 THz frequency by 10x over NEC's existing product. NEC currently produces and markets a THz camera IRV-T0831 equipped with a 320X240-pixel array sensor. However, NEC's latest pixel enables it to develop and produce a 640X480-pixel array sensor which has four times the number of pixels than the current model. NEC has also developed a camera equipped with the array sensor, making it one of the world's largest number of pixels at a THz frequency band.

"NEC has been addressing the development of a highly sensitive real-time uncooled terahertz camera and the improvement in the sensitivity of terahertz array sensors since the development of a highly sensitive bolometer-type uncooled two-dimensional terahertz array sensor in April 2008," said Dr. Naoki Oda, Executive Engineer, Radio Application, Guidance and Electro-Optics Division, NEC. "Going forward, NEC will pursue the development and production of terahertz imaging equipment using the present results and contribute to a variety of fields such as non-destructive inspection, medicine/drug development, and illegal object detection."

To improve the sensitivity, NEC expands the length of the optical cavity structure from 3 - 4 μm of the conventional value to 15 μm, which is formed between a thick metallic layer (perfect reflector) on a readout integrated circuit and thin metallic layer (THz absorber) on a pixel:

Conventional pixel used in the existing THz camera IR/V-T0831

New pixel structure with a thick SiN layer to extend optical cavity length