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A ultra-high performance p-type semiconductor material "Ph-BTBT-10"

 

A ultra-high performance p-type semiconductor material: Ph-BTBT-10 [D5491]

Ph-BTBT-10, an SmE liquid crystalline material, has been recently reported by Hanna et al1) as a p-type material which possesses excellent transport properties. Ph-BTBT-10 exhibits ultra-high mobility (μmax = 14.7 cm2/Vs) comparable to oxide semiconductors (IGZO), and remarkable air stability.1)

TCI has recently commercialized Ph-BTBT-10 as a ultra-high mobility and air stability p-type OFET material, and has begun fabrication and evaluation of Ph-BTBT-10-based OFET devices using by vacuum deposition methods in our laboratories. The devise showed a hole carrier mobility up to 14.0 cm2/Vs. Please see below for the details.

 

Fabrication and Evaluation of Ph-BTBT-10-based OFET Device

The field-effect mobility of Ph-BTBT-10 was measured using the top-contact thin-film field-effect transistors geometry (Figure 1). The thin film of Ph-BTBT-10 as the active layer (40 nm) was vacuum-deposited onto Si/SiO2 substrate (bare) or Octadecyltrichlorosilane (ODTS) [O0079]-treated Si/SiO2 substrate while heating the substrate. The drain and source electrodes (40 nm) then were prepared by gold evaporation through a shadow mask on top of the Ph-BTBT-10 film; the drain-source channel length (L) and width (w) are 50 µm and 1.5 mm, respectively. After deposition, these devices are thermal annealed at Tsub = 120 °C for 5 min under the ambient conditions, and the characteristics of the OFET devices were measured.

Illustration for the device structure of Ph-BTBT-10-based OFETs

Figure 1. Illustration for the device structure of Ph-BTBT-10-based OFETs

The performances of the OFET devices are summarized in Table 1 and Figure 2. All Ph-BTBT-10-based devices exhibited pure typical p-channel field-effect transistor (FET) characteristics. The FET mobilities were quite dependent on the thermal annealing treatment regardless of the self-assemble-monolayer (SAM) (Figure 2). This would be attributed to the phase transition from a monolayer to a bilayer crystal structure in the thin-film form.1)
The device fabricated on the bare substrate demonstrated good performance with a hole carrier mobility of 4.86 cm2/Vs and threshold voltage (Vth) of -8 V. Moreover, although Vth increased, the ODTS-treated devise showed the highest transport performance with a hole carrier mobility of 14.0 cm2/Vs. These results indicate that Ph-BTBT-10 can be handled through vacuum deposition methods, and it is a promising p-type OFET material possessing highly superior hole mobility. We demonstrated the top-ranked FET performances via vacuum deposition process using our in-house equipment.
Currently, we working on the optimization of device fabrication and investigating the correlation between device performance and the thin-film crystallinity.

OFET characteristics of the Ph-BTBT-10-based devices

Table 1. OFET characteristics of the Ph-BTBT-10-based devices

 

Transfer curves of the Ph-BTBT-10-based OFET devices

Figure 2. Transfer curves of the Ph-BTBT-10-based OFET devices

Material purity is an important factor directly influencing their OFET device parameters. To check and enhance the quality and purity of the transistor materials, TCI has recently begun the fabrication and evaluation of the OFET devices using our products. We always seek to improve our technology and skill in order to provide high-purity and quality materials.

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