Organic CMOS image sensor with photoelectric conversion layer is 20% more sensitive
Applied to image sensors in digital cameras and other imaging devices, the technology is said to combine the industry’s highest dynamic range at 88dB while being 1.2 times more sensitive than conventional sensors. This together with a wider incident light angle prevents highlight clipping in bright scenes and the capture of dark subjects with vivid colours and rich textures.
A conventional image sensor consists of a silicon photodiode for capturing light, metal interconnect, color filter and on-chip micro-lens. The newly-developed organic CMOS image sensor technology uses organic photoelectric conversion layer with high absorption coefficient instead of the silicon photodiode, reducing the thickness of the light receiving section down to 0.5 microns – see the picture below.
This structure has improved the signal saturation value by four folds compared to that of conventional image sensors, claims Panasonic. The transistors and metal interconnects in each pixel, fabricated using Panasonic’s semiconductor device technology, are coated with a photoelectric conversion layer, developed using Fujifilm’s organic materials.
While the area of the light receiving section becomes limited in conventional image sensors due to the existence of metal interconnects and the use of a light shield film to prevent light incidence into adjacent pixels, the organic CMOS image sensor can harvest all the light received on the sensor.
The thickness of the organic film featuring a high absorption coefficient has been reduced to just 0.5 microns, a fraction of the thickness of conventional silicon photodiodes which have a depth of typically at least 3 microns. The thinner film expands the light incidence to 60 degrees (from typically 30 to 40º), making a more efficient use of the light impacting the sensor. It also gives greater flexibility in lens designs, facilitating the reduction of overall camera size.
Fujifilm has developed a process technology to produce inorganic barrier films that protect the organic film and prevent the entry of moisture and oxygen. This safeguards the organic conversion layer against performance degradation.
Source and images: Fujifilm
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
