E-book reader

摘要

An e-book reader including a display panel having a thin film transistor with stable electrical characteristics is provided. Alternatively, an e-book reader capable of holding images for a long time is provided. Alternatively, a high-resolution e-book reader is provided. Alternatively, an e-book reader with low power consumption is provided. Display on the display panel of the e-book reader is controlled by a thin film transistor whose channel formation region is formed using an oxide semiconductor which is an intrinsic or substantially intrinsic semiconductor by removal of an impurity that might be an electron donor in the oxide semiconductor and has a larger energy gap than a silicon semiconductor.

主权项

1. An e-book reader comprising:
a transistor including a gate electrode, a gate insulating film, an oxide semiconductor film, a source electrode and a drain electrode; a pixel electrode electrically connected to the oxide semiconductor film; a common electrode facing the pixel electrode; and a display panel including a display medium between the pixel electrode and the common electrode, wherein a concentration of hydrogen in the oxide semiconductor film measured by secondary ion mass spectrometry is 5×1019/cm3 or lower, wherein an outer periphery of the gate electrode has a circular shape with a circular opening at a center thereof when viewed from a top of the transistor, and wherein the oxide semiconductor film is over and in contact with one of the source electrode and the drain electrode, and the other of the source electrode and the drain electrode is over and in contact with the oxide semiconductor film.