[paper] Organic Permeable Base Transistors

Darbandy, G., Dollinger, F., Formánek, P., Hübner, R., Resch, S., Roemer, C., Fischer, A., Leo, K., Kloes, A., Kleemann, H., 

Unraveling Structure and Device Operation of Organic Permeable Base Transistors

Adv. Electron. Mater. 2020, 2000230 

DOI 10.1002/aelm.202000230

Abstract: Organic permeable base transistors (OPBTs) are of great interest for flexible electronic circuits, as they offer very large on‐current density and a record‐high transition frequency. They rely on a vertical device architecture with current transport through native pinholes in a central base electrode. This study investigates the impact of pinhole density and pinhole diameter on the DC device performance in OPBTs based on experimental data and TCAD simulation results. A pinhole density of N Pin = 54 µm−2 and pinhole diameters around L Pin = 15 nm are found in the devices. Simulations show that a variation of pinhole diameter and density around these numbers has only a minor impact on the DC device characteristics. A variation of the pinhole diameter and density by up to 100% lead to a deviation of less than 4% in threshold voltage, on/off current ratio, and subthreshold slope. Hence, the fabrication of OPBTs with reliable device characteristics is possible regardless of statistical deviations in thin film formation.

Fig.: Device stack of an OPBT. The central base electrode is permeable to electrons. The device current flows between emitter and collector, while the base layer is passivated by an oxide layer.

The device current can be modulated by the base‐emitter voltage V_BE

Acknowledgements: G.D. and F.D. contributed equally to this work. This project was funded by the German Research Foundation (DFG) under the grants KL 1042/9‐2 and LE 747/52‐2 (SPP FFlexCom) and by the European Community’s Seventh Framework Programme under Grant Agreement No. FP7‐267995 (NUDEV). This work was supported in part by the German Research Foundation (DFG) within the Cluster of Excellence Center for Advancing Electronics Dresden (cfaed) and the DFG project HEFOS (Grant No. FI 2449/1‐1). Furthermore, the use of HZDR Ion Beam Center TEM facilities and the funding of TEM Talos by the German Federal Ministry of Education of Research (BMBF; grant No. 03SF0451) in the frame‐work of HEMCP are acknowledged. The authors thank Tobias Günther and Andreas Wendel of IAPP for sample preparation.