Advanced Functionalities in Organic Permeable Base Transistors

Vertical transistor architectures offer sub-micrometer channel dimensions and hence, high-frequency operation, without the need for advanced patterning techniques. However, while the fabrication procedures for lateral thin-film transistors matured, fabrication techniques for vertical organic transistors are less developed and as a consequence, yield, uniformity, and reliability of such devices remain poor. Furthermore, reports with vertical organic transistors addressing circuits and advanced device functionalities are rare.<br/>For more than one decade, we have been developing organic permeable base transistors (OPBTs) – a vertical transistor structure that resembles a solid-state triode where nano-scale pinholes allow the current to pass from the emitter to the collector electrode through a control base. Starting with investigations on the fundamental device physics, we advanced the performance of these devices towards the ultra-high-frequencies region, and recently, we demonstrated the integration of complementary inverters with adjustable tripping point. In this contribution, I will discuss recent significant progress concerning device integration using large-area electrochemical anodization. In particular, using this technique, the yield of fabrication is close to 100%, allowing us to integrate circuits. Furthermore, the anodization gives us control over leakage currents, and device capacitance, and increases the tolerances against thickness variation, resulting in an excellent current gain of &gt;10⁷. Moreover, the anodization technique is vital for the realization of devices with advanced functionalities such as vertical memory or reconfigurable devices, opening up the perspective for the design of ultra-high-frequency application-specific circuits based on organic semiconductors.