Hexagonal a-Si:H TFTs: A New Advanced Technology for Flat-Panel Displays

Abstract

Abstract-Inverted stagger hexagonal hydrogenated amorphous silicon thin-film transistors (a-Si:H HEX-TFTs) were fabricated with a five-photomask process used in the processing of the active-matrix liquid crystal displays. We show that the output current of a-Si:H HEX-TFTs connected in parallel increases linearly with their number within a given pixel circuit. Current-voltage measurements indicate that a high ON-OFF current ratio and a low subthreshold slope can be maintained for multiple HEX-TFTs connected in parallel, whereas the field-effect mobility and threshold voltage remain identical to a single a-Si:H HEX-TFT. Due to a unique device geometry, an enhanced electrical stability and a larger pixel aperture ratio can be achieved in the multiple a-Si:H HEX-TFT in comparison to a standard single a-Si:H TFT having the same channel width. These HEX-TFT electrical characteristics are very desirable for active-matrix organic light-emitting displays.Index Terms-Hexagonal thin-film transistor (HEX-TFT), hydrogenate amorphous silicon (a-Si:H), large channel width, multiple transistor, parallel connected.

Electrical stabilities of half-Corbino thin-film transistors with different gate geometries

“…The source of the TFT was grounded while the stress current was set at 4 μA. The stress current reflects the current level that corresponds to the OLED luminance of 10,000 cd/m 2 for the emission efficiency of 12.5 cd/A and the 100 × 50 μm 2 pixel size [12]. The threshold voltages were extracted using the maximum slope method, which determines the threshold voltages as the extrapolation of the current curve with the maximum slope to zero current over the stress time.…”

Trends in Low‐Temperature Combustion Derived Thin Films for Solution‐Processed Electronics

“…[ 17 ] On the other hand, a‐Si:H based TFTs drive the largest market of televisions due to its large‐scale uniformity, ease of scalability, and low‐cost production. [ 18,19 ] Although a‐Si:H is a popular candidate for the mainstream backplane of displays, yet its carrier μ is severely limited (0.5–1.0 cm 2 V −1 s −1 ). [ 15 ] Also, the limitations such as inferior current‐carrying capacity, optical opacity, and moderate mechanical flexibility impose challenges for advanced large scale, flexible electronics.…”

Asymmetric Electrical Properties of Half Corbino Hydrogenated Amorphous Silicon Thin-Film Transistor and Its Applications to Flat Panel Displays

“…18) Therefore, the power consumption will be reduced since the programmed gate voltage variation is caused by the feed-through effect of C GS . 19) During the driving state, the power consumption becomes a static model due to the DC bias (V DD ) on the driving transistor, and it can be defined as P TFT ¼ V 2 DD =R TFT where R TFT is the channel resistance determined by V GS (gate node voltage defined at the programming stage). Therefore, in order to reduce the V DD level, we need to use a transistor with a large channel width (W=L can be large).…”