Effects of dopants in InOx-based amorphous oxide semiconductors for thin-film transistor applications

Abstract

Amorphous metal oxide thin-film transistors (TFT) are fabricated using InO x -based semiconductors doped with TiO 2 , WO 3 or SiO 2 . Although density of dopant is low in the film, change in the electrical properties showed strong dependence on the dopant species. We found that the dependence could be reasonably explained by the bond-dissociation energy. By incorporating the dopant with higher bond-dissociation energy, the film becomes less sensitive to oxygen partial pressure used during sputtering deposition and remains electrically stable to thermal annealing treatment. The concept of bond-dissociation energy can contribute to the realization of more stable metal oxide TFTs for flat panel displays.

Low-temperature processable amorphous In-W-O thin-film transistors with high mobility and stability

“…15 Previously, we investigated the effects of dopants in In-X-O (X ¼ Si, Ti or W) semiconductors based on the oxygen bond-dissociation energy. 19 In the current study, highly stable TFTs with high field-effect mobilities that use a W-doped InO x (IWO) semiconductor film deposited using a dry sputtering technique at room temperature are reported. The conventional dry deposition technique is scalable and is compatible with the commercial production of flat-panel displays.…”

“…This is attributed to the high oxygen bond-dissociation energy of W (720 kJ/mol). 19,30 Because the W dopant is expected to suppress the formation of excess oxygen vacancies, the trap density that originates from the vacancies decreases, and the DV ON consequently decreases with the incorporation of WO 3 . The shift in the V ON is related to the interfacial trap density (N it ) between the semiconductor and the gate insulator, 31 which is determined using the following equation: 32…”

“…Recently, InO x -based amorphous oxide semiconductors such as In 2 O 3 , 7,8 InZnO, 9,10 Sn-InZnO, 11 Hf-InZnO, 12,13 Si-InZnO, 3,14 Zr-InZnO, 15,16 InGaZnO (IGZO), 17 InWO, 18 and InSiO 19,20 have been investigated in low-temperature processes to improve device performance. Because Zn-containing oxide semiconductors are sensitive to moisture in the atmosphere, 21 a ZnO-based TFT that is fabricated at a low temperature is difficult to use in stable operation.…”

Reduction of the interfacial trap density of indium-oxide thin film transistors by incorporation of hafnium and annealing process

“…Thin film transistors based on amorphous oxide films (OxTFTs) have attracted tremendous interest as TFT backplanes in active-matrix organic light emitting diodes (OLEDs) and liquid crystal displays owing to their high mobilities. [1][2][3][4][5][6][7] Intensive developments on oxide compounds including InO x -based, [8][9][10][11][12][13] ZnO x -based, 14 SnO x -based 15 and mixed channel materials such as InZnO x -based OxTFTs [16][17][18][19][20][21][22][23][24][25] have been widely studied in OxTFTs in recent decades because of their excellent electrical stabilities and high mobilities. Among them, InGaZnO (IGZO) 1,2,26 and InSnZnO (ITZO) 18,19 are currently being developed for use as commercial TFT backplanes because of their superior properties and high electron mobilities.…”

“…Because Zn-O (bond-dissociation energy = 159 kJ/mol) has a relatively low bond-dissociation energy compared with In-O (320 kJ/mol), high bond-dissociation energy metals were introduced into the high mobility amorphous InO x films, such as W-InO 8,9 and Si-InO. 10,11 Here, using the high dissociation energy dopant, Hf-O (820 kJ/mol), we investigated a simple semiconducting material, Hf-InO x , with relatively low annealing temperatures (150-250…”