Abstract: The present invention is related to an infrared ray sensor including a substrate having a p-n junction, a ferroelectric film formed on a surface of the substrate for sensing infrared ray, and a metal film formed on the ferroelectric film for serving as an infrared-ray receiving electrode. The present invention is also related to a method for producing the IR sensor including steps of: providing the substrate having the p-n junction; depositing the ferroelectric film on the surface of the substrate in a radio frequency (RF) sputtering system; and depositing the metal film on the ferroelectric film by vapor evaporation. Alternatively, the deposition of the ferroelectric film on the surface of the substrate can be performed in a KrF pulse-mode laser evaporation system.

Abstract: A gas sensor having a large operation current and being operated at a relatively low temperature includes a substrate having a first surface and a second surface. A sensing area is provided on the first surface for increasing the conductivity across it when the sensing area detects a certain gas. A controlling area is provided on the first surface and beside the sensing area for permitting a tunneling current to pass therethrough when the sensing area cannot sense a certain gas or when the gas sensor is adapted to be sufficiently supplied with power. This control area prevents the tunneling current from being generated when the sensing area detects certain gas and thus the conductivity is increased, so that when the first and the second surfaces are electrically connected to the power supply. The gas sensor will be in an on state when the gas sensor cannot sense there is the certain gas and be in an off state when the gas sensor detects the presence of certain gas.