Room-Temperature Fabrication of HfON Gate Insulator for Low-Voltage-Operating Pentacene-Based Organic Field-Effect Transistors

Abstract

Low-voltage-operating pentacene-based organic field-effect transistors (OFETs) with different channel lengths have been fabricated by employing a room-temperature-processed HfON gate insulator. It was found that the on/off current ratio of the OFETs can be improved by decreasing the channel length. However, the hole mobility in the OFETs decreases with decreasing channel length owing to the effect of contact resistance. Interestingly, such OFETs with a short channel length (channel W/L = 500/50 µm) also show good electrical properties, such as a high hole mobility of 0.26 cm2 V-1 s-1, a low subthreshold swing of 0.13 V/decade, and a large on/off current ratio of 1×105 at an operating voltage of -2 V.

Ultrathin Poly(4-vinylphenol) Interfacial Layer Evaporation for Low-Voltage Operation of Organic Field-Effect Transistors with HfO2 Gate Insulator

“…The surface roughness of 5-nm-thick HfO 2 is indicated by the dotted line (rms: 0.19 nm), which is smaller than those of other high-k gate insulators and polymer/high-k stack gate insulators in spite of RT deposition. 17,[21][22][23][24][25][26] An rms surface roughness of 0.28 nm was observed for PVP deposited at RT, while it decreased to 0.11 nm for the PVP films deposited at 50-100 C.…”

“…Bottom-gate-type pentacenebased OFETs were fabricated on n þ -Si(100) substrates (resistivity, 1-6 m cm) with a top-contact bottom-gate device geometry. [14][15][16][17][18] First, n þ -Si(100) substrates were chemically cleaned by a sulfuric peroxide mixture (SPM) and diluted hydrofluoric acid (DHF). Next, a 0.7-nm-thick chemical oxide (C'O) layer was formed on the Si substrates by immersion in 30% H 2 O 2 solution for 60 min at room temperature to improve the interface quality.…”