Low voltage operation organic phototransistor with vertical configuration

Abstract

From the wisdom of conventional silicon technology, organic vertical field-effect transistors (VFETs) have recently been explored as a promising device platform that may help overcome the limitation of conventional lateral channel field-effect transistor structures[1,2]. The channel length of VFETs is ultimately defined as its active layer thickness, which can be easily down-scaled to sub-μm without costly complex fabrication. As a result, VFETs can produce a higher output current than the conventional lateral channel device structure due to its vertical configuration. In this work, we demonstrate the organic phototransistor with vertical channel structure and investigate their operation mechanism. The vertical phototransistor showed a responsivity of 290 A/W and response with a low light intensity of 7.5 μW/cm2. It was also possible to operate at low voltage and show much greater performances than the lateral channel phototransistor owing to its vertical channel structure. In addition, we control device parameters influencing its device performance using a 2D device simulations to get better understanding of its operation mechanism. This results allowed us to define design rules for realization of high-performance vertical phototransistor.