Radio-Frequency Polymer Field-Effect Transistors Characterized by S-Parameters

M Giorgio,M Caironi

doi:10.1109/led.2019.2909844

Abstract

Thanks to recent progress in terms of materials properties, polymer field-effect transistors (FETs) operating in the MHz range can be achieved. However, further development towards challenging frequency ranges, for a field accustomed to slow electronic devices, has to be addressed with suitable device design and measurements methodologies. In this work, we report n-type FETs based on a solution-processed polymer semiconductor where the critical features have been realized by a large-area compatible direct-writing technique, allowing to obtain a maximum frequency of transition of 19 MHz, as measured by means of Scattering Parameters (S-Parameters). This is the first report of solution-processed organic FETs characterized with S-Parameters.

Highlights

O RGANIC electronics underwent an impressive development and thanks to its peculiar properties, e.g. high degree of tunability of electronic properties and thin molecular films deposition with scalable processes at low temperature on a wide variety of substrates, represent one of the most promising candidates in the path to ubiquitous, flexible and lightweight low-cost electronics.To date, organic light emitting diodes (OLEDs) [1] have reached commercial maturity, and significant progress has been achieved for organic solar cells [2], photodetectors [3], biosensors [4] and circuits based on organic transistors [5]
Organic light emitting diodes (OLEDs) [1] have reached commercial maturity, and significant progress has been achieved for organic solar cells [2], photodetectors [3], biosensors [4] and circuits based on organic transistors [5]
In the case of field effect transistors (FETs), the use of polymer semiconductors has the advantage of achieving superior mechanical properties and enabling large-area fabrication techniques, such as printing

Summary

INTRODUCTION

O RGANIC electronics underwent an impressive development and thanks to its peculiar properties, e.g. high degree of tunability of electronic properties and thin molecular films deposition with scalable processes at low temperature on a wide variety of substrates, represent one of the most promising candidates in the path to ubiquitous, flexible and lightweight low-cost electronics. For polymer FETs instead, an fT above 10 MHz was achieved thanks to extrapolation in two cases, in which the device was fabricated by combining direct-writing and printing techniques [17], [18]. It is not possible to rely further on direct measurement methods for characterizing the upcoming organic high-frequency devices S-parameters were adopted only by one group for measuring a maximum fT of 6.7 MHz in organic FETs based on an evaporated small-molecule semiconductor, and realized by using silicon stencil masks to define critical lateral features in the submicron range [23]–[25]. We adopted S-parameters to characterize solution-processed polymer FETs where critical features have been realized by a direct-writing, large-area compatible technique. For the shortest channel length transistor we obtained a maximum fT of 19 MHz at the relatively low applied gate-source voltage VGS of 12 V

OFETS FABRICATION PROCESS

CONCLUSIONS