Low Temperature ZnO TFTs Fabrication with Al and AZO Contacts for Flexible Transparent Applications

Abstract

Zinc Oxide (ZnO) Thin-Film Transistors (TFTs) using Aluminum (Al) and Aluminum-doped zinc Oxide (AZO) as Source-Drain (S-D) contacts are reported. The fabrication process was carried out using five photolithography steps with a maximum processing temperature of 100 ˚C, which makes the process compatible with flexible/transparent applications. The AZO and ZnO films were deposited using Pulsed Laser Deposition (PLD). Aluminum was deposited using ebeam. The devices showed mobilities >10 cm 2 /V-s, threshold voltage in the range of 7 V and On/Off current ratios >10 5 . The resistance analysis showed that AZO is a better contact with lower contact resistance as identified in the TFTs. The AZO and ZnO stacks characterized by UV-V shows an optical transmission >80 %.

Zinc oxide integrated area efficient high output low power wavy channel thin film transistor

“…For the drain current, the drain current value for the planar device is comparable to other reports in the literature for ALD based ZnO TFTs. [10][11][12][13] As for the drain currents for the fin devices, they are shown also as a function of the number of in Fig. 4(b).…”

Bias stress study of Metal-Insulator-Semiconductor structures with pulsed laser deposited InGaZnO on atomic layer deposited HfO2

“…In this regard, are highly relevant the research works focused on TFTs fabrication over large areas with uniform device properties, the use of suitable materials for transparent and flexible electronics, as well as the implementation of low cost procedures that guarantee its successful application in the upcoming generations of active matrix liquid crystal displays (AMLCD) and organic light-emitting diode displays (AMOLED) [2,3]. To overcome these challenges, many efforts have been dedicated to improve the TFTs performance, to apply low temperature and significantly inexpensive fabrication techniques, moreover, to enhance their reliability [4][5][6].…”

“…Amorphous oxide semiconductors (AOS) are considered the most promising materials for TFTs because they can provide higher field effect mobility values than amorphous silicon, the possibility of fabrication over large areas with uniform device properties and high optical transparency by using conventional deposition techniques at low temperature [4][5][6]. In order to enhance the transistor performance, amorphous oxide compounds such as Indium-Zinc Oxide (IZO), Indium-Gallium-Zinc oxide (IGZO) or HafniumIndium-Zinc oxide (HIZO) are under investigation as active layers for TFTs fabrication [5,7,8].…”

“…Moreover, by using gate insulating layers with high dielectric constants that allow to reduce tunneling leakage currents, as well as, the operating voltage and the subthreshold swing of the TFT. Thus, hafnium oxide (HfO 2 ) is being highly considered as gate dielectric material [2,3,6,9].…”

Improvement in n-ZnO/p-Si diode properties using ZnO/AZO homogeneous metal contact

“…The transfer length method was used to determine contact resistance. [15][16][17] Thermal stability was analyzed with varying substrate temperature from 300 to 450 K.…”