Abstract
Issues of amorphous oxide semiconductors (AOSs) thin-film transistors (TFTs) mainly focus on improving electrical performance and stability. Currently, the hump, the abnormal transfer characteristic, is also an essential factor of AOSs TFT. The hump phenomenon was observed for AOS-TFTs with a metal capping (MC) layer under various measurement conditions. The mobility in the MC TFT was improved from 14.8 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs to 19.2 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs compared to that of the conventional TFTs. The improved electrical characteristics in the MC structure are representative of the carrier injection effect and the change of the current path. This reason reveals that the MC structure has a hump phenomenon under the low drain to source voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{DS}$ </tex-math></inline-formula> ). The hump characteristic does not significantly affect the overall MC TFT characteristics (transfer characteristic, improved electrical characteristics through MC structure, etc.). In addition, it was confirmed that it exhibits very stable hump characteristics through repeated measurements and uniformity. It was found that two current paths are formed mainly due to carrier injection from the metal capping layer in the hump phenomenon observed at low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{DS}$ </tex-math></inline-formula> . These divided current paths can lead to two on-currents ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{on}$ </tex-math></inline-formula> ) in the transfer curve. Many studies have recently been conducted to fabricate semiconductor devices with multi-values such as 0, 1, and 2. This divided current path could propose a simple method to achieve multi-values with an easy process.
Highlights
As semiconductor materials that could be applied to the next-generation application technologies, the amorphous oxide materials have emerged as a strong candidate [1]–[4]
In summary, the analysis of metal capping (MC) thin-film transistors (TFTs) that can improve electrical characteristics has been performed in terms of the hump phenomenon
The μFE of metal capping layer TFT (MC TFT) was improved from 14.82 cm2/Vs to 19.37 cm2/Vs and S.S value from 0.56 V/decade to 0.37 V/decade, respectively, compared to the conventional structure
Summary
As semiconductor materials that could be applied to the next-generation application technologies, the amorphous oxide materials have emerged as a strong candidate [1]–[4]. Many previous studies exist to enhance the properties of amorphous oxide materials used TFTs with various structures, such as multi-stack, bi-layer, and materials doping [10]–[13]. These structures have disadvantages, such as adding or complicated processes. We analyzed the hump phenomenon in the origin state of MC layer TFT without applying stress. It is exciting to observe and analyze that the hump phenomenon appeared in metal capping layer TFT (MC TFT) even at the origin state before being stressed externally. We expect it to be applied to various next-generation device applications, such as multi-value transistors, by adopting negative differential transconductance by the cause of hump generated in this study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
