We report an all-printed thin-film transistor (TFT) on a polyimide substrate with linear transconductance response. The TFT is based on our purified single-walled carbon nanotube (SWCNT) solution that is primarily consists of semiconducting carbon nanotubes (CNTs) with low metal impurities. The all-printed TFT exhibits a high ON/OFF ratio of around 103 and bias-independent transconductance over a certain gate bias range. Such bias-independent transconductance property is different from that of conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) due to the special band structure and the one-dimensional (1D) quantum confined density of state (DOS) of CNTs. The bias-independent transconductance promises modulation linearity for analog electronics. 1. Introduction Printable flexible electronics technology offers a cost-effective way to achieve mass production of large-area flexible electronic circuits without using special lithography equipment. It is expected to offer an enabling technology for numerous applications, particularly those that require or may benefit from the use of flexible polymeric substrates, such as inflatable antennas, electronic papers, RF identification (RFID) tags, smart skins, and flat panel displays. Due to its mechanical flexibility and high field effect mobility, carbon nanotube (CNT) has shown great promises in printable flexible electronics [1–5]. High mobility and high-speed CNT-based printable thin-film transistor (TFT) have been demonstrated [6–10]. In addition to its mechanical flexibility and high field effect mobility, CNT is also a promising material for transistors with bias-independent transconductance due to the special band structure and the one-dimensional (1D) quantum confined density of state (DOS) of CNTs [11–14]. The band structure and the 1D DOS of CNT allow the CNT-based TFTs to possess near-ballistic electron transportation and bias-independent transconductance [12, 13]. Such bias-independent transconductance is called inherent linearity [12] (referred it to as linear response or linear CNT-TFT, henceforth). The bias-independent transconductance is different from conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) and is highly desired in many analog RF devices such as low noise amplifiers and power amplifiers [11–13]. However, most linear CNT-TFTs reported to date are based on CNTs grown by using the chemical vapor deposition (CVD) grown method [12, 13] to obtain semiconducting CNTs with good alignment between the source (S) and drain (D) electrodes [13]. While high
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