Amorphous silicon (a–Si), one of the substances used for thin-film transistors (TFTs), was widely used in the early stages of LCDs and has been used for its simple and fast properties, plus its high yield. However, the need for a new material to replace a–Si was raised as there were difficulties reproducing clearer image quality. Oxide TFTs appeared as a savior that could compensate for the shortcomings of a–Si.
Oxide TFTs use a metal oxide compound as a semiconductor, so named because it contains both metals and oxygen in its structure. Specifically, the metal oxide used is a complex arrangement of the elements indium (In), gallium (Ga), zinc (Zn) and oxygen (O), like in the diagram above.
The advantages of Oxide TFTs
The outstanding advantage of oxide TFTs is the speed of electron movement. Unlike a–Si TFTs, which have low electron transfer rates due to irregular atomic arrangements, oxide TFTs boast about 10 times faster electron transfer rates thanks to the semiconductor properties of oxide materials. The faster the electron travels, the faster the signal transmission speed, which is advantageous for relatively high definition. In addition, a–Si process facilities can be utilized as they are for oxide TFTs, so production costs are more efficient, and the atomic arrangement in its amorphous form is uniform, so it is possible to spread the compound uniformly over a large area to easily produce large-sized displays. Finally, oxide TFTs appear transparent to the electromagnetic waves that can be seen with human eyes, meaning that it can be used to produce Transparent OLEDs.
