Kun-Chih Lin

Silicon nanocrystal-based photosensor on low-temperature polycrystalline-silicon panels

A photodetector, comprising a layer of silicon nanocrystals that is sandwiched between two electrodes, is proposed and demonstrated in a photosensing application on low-temperature polysilicon panels. Laser annealing of silicon-rich oxide films can form nanocrystals that respond optimally to a certain absorption spectrum of a light source. These silicon nanocrystals are smaller than 10nm in diameter, which size determines the effectiveness of their quantum confinement, and promote electron-hole pair generation in the photosensing region because of their direct band gap. Besides obtaining a photosensitivity that is comparable to that of a p‐i‐n diode, which is currently used in low-temperature polysilicon technology, the sensor maximizes the photosensing area of a pixel by its stacked structure.

Silicon-nanocrystal-based photosensor integrated on low-temperature polysilicon panels

— A photodetector using a silicon-nanocrystal layer sandwiched between two electrodes is proposed and demonstrated on a glass substrate fabricated by low-temperature poly-silicon (LTPS) technology. Through post excimer-laser annealing (ELA) of silicon-rich oxide films, silicon nanocrystals formed between the bottom metal and top indium thin oxide (ITO) layers exhibit good uniformity, reliable optical response, and tunable absorption spectrum. Due to the quantum confinement effect leading to enhanced phonon-assisted excitation, these silicon nanocrystals, less than 10 nm in diameter, promote electron-hole-pair generation in the photo-sensing region as a result resembling a direct-gap transition. The desired optical absorption spectrum can be obtained by determining the thickness and silicon concentration of the deposited silicon-rich oxide films as well as the power of post laser annealing. In addition to obtaining a photosensitivity comparable to that of the p-i-n photodiode currently used in LTPS technology, the silicon-nanocrystal-based photosensor provides an effective backlight shielding by the bottom electrode made of molybdenum (Mo). Having a higher temperature tolerance for both the dark current and optical responsibility and maximizing the photosensing area in a pixel circuit by adopting a stack structure, this novel photosensor can be a promising candidate for realizing an optical touch function on a LTPS panel.

P-199L: Late-News Poster: Silicon Nanocrystals Photo Sensor Integrated on Low-Temperature Polycrystalline-Silicon Panels

A photo-detector using silicon nanocrystal layer sandwiched between two electrodes is first time proposed and demonstrated for photo-sensing application on LTPS panels. Through post-annealing of silicon rich oxide films, Si nanocrystals can be formed with good uniformity and high temperature tolerance to respond best to certain absorption spectrum of the corresponding light source. These silicon nanocrystals, less than 10nm in diameter, exhibit better quantum confinement effect, which promote electron-hole pair generation in photo-sensing region as a result of its direct bandgap. In addition to obtaining photo sensitivity superior to that of a P-I-N diode currently used in LTPS technology, the new sensor can maximize the fill factor in a pixel circuit by adapting a stacked structure.