Sharp, SEL Revamp IGZO TFT

Jun 5, 2012
Shinya Saeki, Nikkei Electronics
The 6.1-inch LCD panel for mobile devices such as tablet computers
The 6.1-inch LCD panel for mobile devices such as tablet computers
[Click to enlarge image]
The 4.9-inch LCD panel for smartphones
The 4.9-inch LCD panel for smartphones
[Click to enlarge image]
The 13.5-inch OLED panel. There are a few missing longitudinal lines.
The 13.5-inch OLED panel. There are a few missing longitudinal lines.
[Click to enlarge image]
The 3.4-inch flexible OLED panel
The 3.4-inch flexible OLED panel
[Click to enlarge image]

Sharp Corp and Semiconductor Energy Laboratory (SEL) Co Ltd announced June 1, 2012, that they have developed an IGZO (In-Ga-Zn-O)-based TFT having properties improved by adding crystallinity.

The companies expect that the TFT will be used as driver elements of LCD and OLED panels for smartphones, tablet computers, etc, whose resolutions are becoming higher. Sharp plans to start volume production of an LCD panel using the new IGZO TFT within fiscal 2012 though it depends on customer demand, it said.

At a press conference that Sharp had June 1, 2012, the company showed LCD and OLED panels that use the newly-developed IGZO TFT. It showcased a 4.9-inch LCD panel whose pixel count and resolution are 1,280 x 720 and 302ppi and a 6.1-inch LCD panel with a pixel count of 2,560 x 1,600 and 498ppi.

"We have established a technology to mass-produce an LCD panel with a resolution of up to 500ppi with no problem," the company said.

Asked how Sharp will deal with its "CG silicon" TFT, which uses a low-temperature polysilicon TFT, in the future, it said, "Though it depends on users, it is sure that we will shift our focus to IGZO TFT."

As for the OLED panels, Sharp showed 13.5- and 3.4-inch panels whose pixel counts are 3,840 x 2,160 and 960 x 540, respectively. Their resolutions are both 326ppi. The 13.5-inch panel realizes color display by using red, green and blue (RGB) color filters for its white OLED devices. The 3.4-inch panel is flexible because it uses a resin substrate. The company did not disclose the material of the OLED device, light extraction method, etc because "the panels are just prototypes."

Sharp considers that OLED panel is important as "one field of mobile display." But, asked about its commercialization schedule, the company said, "Though it is technically possible, there are financial challenges such as costs as well as issues related to investment effect."

Crystal growth in c-axis direction

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