Organic Zener Diodes: Tunneling across the Gap in Organic Semiconductor Materials

TL;DR

This paper reports the development of organic Zener diodes with precisely tunable reverse breakdown voltages, achieved by controlling the depletion zone width, and explains the tunneling mechanism underlying their operation.

Contribution

It introduces a method to precisely control the breakdown voltage in organic Zener diodes by adjusting depletion width independently of doping and layer thickness.

Findings

Reverse breakdown voltage tunable from -3 V to -15 V

Breakdown behavior explained by tunneling across HOMO-LUMO gap

Experimental data supported by a minimal Hamiltonian model

Abstract

Organic Zener diodes with a precisely adjustable reverse breakdown from -3 V to -15 V without any influence on the forward current-voltage curve are realized. This is accomplished by controlling the width of the charge depletion zone in a pin-diode with an accuracy of one nanometer independently of the doping concentration and the thickness of the intrinsic layer. The breakdown effect with its exponential current voltage behavior and a weak temperature dependence is explained by a tunneling mechanism across the HOMO-LUMO gap of neigh- boring molecules. The experimental data are confirmed by a minimal Hamiltonian model approach, including coherent tunneling and incoherent hopping processes as possible charge transport pathways through the effective device region.