Interface Characteristics between Au Electrode and Pentacene Layer in Organic Thin-film Transistors

Abstract

In order to investigate interfacial characteristics between top-Au and pentacene layers, devices with the structure of bottom-Au/pentacene/top-Au were fabricated on glass substrates at various deposition rates of top-Au of about 1.0, 3.0 and 15.0 Å/s. It was observed that electrical characteristics could be improved by increasing the deposition rate of top-Au, and the highest electrical conductivity value, 1.5×10-6 S/cm, was obtained for the device with top-Au deposited at 15.0 Å/s. Auger electron spectroscopy (AES) results showed that the atomic content of Au is substantially increased with the deposition rate of top-Au, but there is no marked difference in the depth profile of Au atoms regardless of the deposition rate of top-Au. Likewise, field-emission scanning electron microscopy (FE-SEM) images did not reveal structural defects that might cause short circuit. We also fabricated top-contact organic thin-film transistors (OTFTs) at various deposition rates of the Au layer for source/drain electrodes. As a result, the performance of the OTFTs can be modified by the deposition rate of Au. These results will be discussed.

Pentacene-based organic field-effect transistors

“…However, the work function depends on the surface condition, as described in section 4.4. The deposition conditions also affect the conductivities of Au, which increase with the deposition rate [107]. This dependence influences the mobility of pentacene TFTs with Au top contact electrodes.…”

Transport characteristics in Au/pentacene/Au diodes

“…Since the pentacene clusters were not tightly packed, some Au clusters entered the gaps between them during the deposition of the top Au layer, which is consistent with previous reports. 18,22) The Au clusters that penetrate the pentacene film are not completely connected, according to the TEM observation [Fig. 1(b)].…”

Gate-bias and temperature dependence of charge transport in dinaphtho[2,3-b:2′,3′-d]thiophene thin-film transistors with MoO3/Au electrodes

“…10) Many researchers have been focusing on improving the device performance of transistors through different methods, particularly through the modification of the organic semiconductor-dielectric and organic semiconductor-electrode interfaces. [11][12][13] Recently, metal oxides such as molybdenum oxide (MoO 3 ), tungsten oxide (WO 3 ), and germanium oxide (GeO) have been used in OTFTs as a buffer layer for carrier injection to improve OTFT performance. [13][14][15][16] It has been confirmed that, by inserting a metal oxide between the electrode and the organic semiconductor layer, the contact resistance at the organic semiconductor-electrode interface could be reduced, thus improving the performance of OTFTs.…”