Highly Reliable Amorphous In-Ga-Zn-O Thin-Film Transistors Through the Addition of Nitrogen Doping

The electrical properties and the device reliability under positive/negative bias stress with/without illumination regarding amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) are evaluated as a function of the nitrogen partial pressure in the sputter deposition. Interestingly, it is easy to control the carrier concentration through the incorporation of nitrogen into IGZO, whereby the device performance is changed. In addition, when nitrogen is introduced during the conventional IGZO deposition, the device reliability of N-doped IGZO TFTs is considerably improved compared to that of undoped-IGZO TFTs due to the reduced amount of defects. It is also interesting that such an improvement of the device reliability regarding IGZO is easily obtainable through the simple addition of nitrogen to the conventional deposition process. It is, therefore, strongly believed that this simple nitrogen-doping process for IGZO is very effective regarding the achievement of highly durable devices, and it can be immediately applied to the current mass production of the high-performance displays for which the oxide semiconductor is used.