Abstract:
A standalone ambient light sensing device was constructed by interfacing a sulphided Cuprous Oxide (Cu2
O)
thin film semiconductor based photo-sensor. The photo-sensor was custom fabricated by depositing n-type Cu2
O on a titanium
substrate followed by a sulphidation process that formed a Cu2
O/Cux
S thin film semiconductor heterojunction. Evaporated
gold contacts were placed on top of the film. The photo-sensor was operated in the photovoltaic mode and once interfaced to
the device, the sensor photovoltage was further amplified and measured through a 10-bit analog to digital voltage converter
embedded in a microcontroller. A liquid crystal display was interfaced to the microcontroller to display measurements. Data
logging was done directly to the available microcontroller flash memory or through a RS-232 serial communication link to
a PC. The sensor was sensitive to a broad range of intensities (0 – 120,000 lux) with a fast photo-response time on the order of
a few hundred milliseconds. The available extra microcontroller ports could be utilized for device control and feedback by
interfacing other suitable electronics. The total cost of parts for the device was less than US$25.
