Interdigitated ITO Substrates for OFET and Sensing

Order Code: S161


(excluding Taxes)


The Ossila pre-patterned ITO OFET substrates have been designed to enable the fabrication and characterisation of transistors without the need for vacuum evaporations or probe stations. This allows devices to be produced and tested with significantly increased simplicity, making the system ideal for reducing costs of material screening experiments; as well as teaching and training purposes.



Substrate specifications.
Substrate size 20 mm x 15 mm
Pack size 100 substrates per standard pack
Thickness 1.1 mm
Channel dimensions

S161: W × L: 30 mm × 50 μm

S162: W × L: 30 mm × 50, 75, 100, 150 and 200 μm

Glass type Polished soda lime, float glass
Substrate coating Fully oxidized ITO
ITO thickness 100 nm
ITO resistance 20 Ω / square
Glass roughness 1 nm RMS (By AFM)
ITO roughness 1.8 nm RMS (By AFM)


The pre-patterned OFET substrates consist of interdigitated ITO fingers to act as the source-drain contacts, and have overall channel dimensions of 30 mm x 50 μm. These relatively large channels work to minimise contact effects, so it is less important to match the energy levels of the organic semiconductor and contacts. As such, the intrinsic Poole Frenkel limited mobility of a material can be more easily assessed independent of the HOMO level. The 30 mm channel width also has the additional benefit of producing larger currents, making testing and measurement quicker and requiring less sensitive (and less expensive) equipment.

The substrate itself is made of high-quality soda-lime float glass with a 20 nm coating of SiO2 (synthetic quartz), which allows for HMDS and OTS treatments to improve mobility. The transparent nature of the ITO/glass also means that opto-electric experiments can be done with ease (photoconductivity, photo-induced doping in the presence of oxygen, sensing).

Transistors can be fabricated by simply depositing an organic semiconductor, gate insulator and gate on the substrates (see diagram below for device schematic). By using a synthetic metal (such as PEDOT:PSS) deposited from solution for the gate, it is possible to make fully-functioning OFETs by solution processing alone, eliminating vacuum evaporation processes. The use of the Ossila OFET test board also means that devices can be measured at the flick of a switch without the need for probe stations.

While all solution-based processing allows transistors to be fabricated in a matter of minutes, the substrates are also designed to work with a wide variety of different material systems and deposition techniques. As such, vacuum-deposited semiconductors, gate insulators and gates can also be used with the appropriate shadow mask.

ITO constant channel length substrate
50 μm channel length substrate dimensions
ITO variable channel length substrate
Variable channel length substrate dimensions


AFM scan of ITO substrate
10 µm x 10 µm AFM scan with Z-scale of ±5 nm.


AFM of glass surface of ITO substrates
AFM of glass surface (1 µm x 1 µm x 3.5 nm). Courtesy of Richard T Grant.


Transmittance of ITO
Transmittance of ITO substrates


To the best of our knowledge, the information provided here is accurate. However, Ossila assume no liability for the accuracy of this information. The values provided here are typical at the time of manufacture and may vary over time and from batch to batch.


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