Highly sensitive electron-emission-type infrared sensor using a single crystalline LiNbO3

We propose a new electron-emission-type infrared light sensor and imager, which uses the principle of electron emission from a ferroelectric material. Previously, we reported that the electron emission current was proportional to the incident infrared light energy and 30% of the pyroelectric current was emitted to the vacuum (Tomita, K. et al., Sensors and Actuators, vol.97-8, p.147-52, 2002). The electron-emission-type infrared sensor is improved by using a single crystalline LiNbO₃ and a secondary electron multiplying device. This type of sensor was proposed and demonstrated previously using Pb(Zr,Ti)O₃ (PZT). The response speed increased to 1.5 times that of PZT. On a pulsed infrared irradiation condition, this sensor achieved infrared light sensitivity of 41 nA/W without multiplication of the emission electrons. It is expected that electrons can be supplied to the surface from the comb-type electrode. The electron emission current was measured, and the peak current did not change during a continuous detection operation. In the low incident light condition, an emission pattern was confirmed by multiplication of emission electrons. This image was caused by the pyroelectric charge from LiNbO₃.