Highly Conductive and Transparent AZO Films Fabricated by PLD as Source/Drain Electrodes for TFTs

Aluminum-doped ZnO (AZO) has huge prospects in the field of conductive electrodes, due to its low price, high transparency, and pro-environment. However, enhancing the conductivity of AZO and realizing ohmic contact between the semiconductor and AZO source/drain (S/D) electrodes without thermal anne...

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Bibliographic Details
Main Authors: Hongke Zhang, Xiaoqing Li, Zhiqiang Fang, Rihui Yao, Xiaochen Zhang, Yuxi Deng, Xubing Lu, Hong Tao, Honglong Ning, Junbiao Peng
Format: Article
Language:English
Published: MDPI AG 2018-12-01
Series:Materials
Subjects:
AZO
PLD
TFT
Online Access:https://www.mdpi.com/1996-1944/11/12/2480
Description
Summary:Aluminum-doped ZnO (AZO) has huge prospects in the field of conductive electrodes, due to its low price, high transparency, and pro-environment. However, enhancing the conductivity of AZO and realizing ohmic contact between the semiconductor and AZO source/drain (S/D) electrodes without thermal annealing remains a challenge. Here, an approach called pulsed laser deposition (PLD) is reported to improve the comprehensive quality of AZO films due to the high energy of the laser and non-existence of the ion damage. The 80-nm-thick AZO S/D electrodes show remarkable optical properties (transparency: 90.43%, optical band gap: 3.42 eV), good electrical properties (resistivity: 16 &#215; 10<sup>&#8722;4</sup> &#937;&#183;cm, hall mobility: 3.47 cm<sup>2</sup>/V&#183;s, carrier concentration: 9.77 &#215; 10<sup>20</sup> cm<sup>&#8722;3</sup>), and superior surface roughness (R<sub>q</sub> = 1.15 nm with scanning area of 5 &#215; 5 &#956;m<sup>2</sup>). More significantly, their corresponding thin film transistor (TFT) with low contact resistance (R<sub>SD</sub> = 0.3 M&#937;) exhibits excellent performance with a saturation mobility (&#181;<sub>sat</sub>) of 8.59 cm<sup>2</sup>/V&#183;s, an I<sub>on</sub>/I<sub>off</sub> ratio of 4.13 &#215; 10<sup>6</sup>, a subthreshold swing (SS) of 0.435 V/decade, as well as good stability under PBS/NBS. Furthermore, the average transparency of the unpatterned multi-films composing this transparent TFT can reach 78.5%. The fabrication of this TFT can be suitably transferred to transparent arrays or flexible substrates, which is in line with the trend of display development.
ISSN:1996-1944