Negative differential resistance in polymer tunnel diodes using atomic layer deposited, TiO2 tunneling barriers at various deposition temperatures

Atomic layer deposition (ALD) presents a method to deposit uniform and conformal thin-film layers with a high degree of control and repeatability. Quantum functional devices that provide opportunities in low-power molecular and organic based memory and logic via thin metal-oxide tunneling layer were previously reported by Yoon et al. [1]. Demonstrated here area polymer tunnel diodes (PTD) with high negative differential resistance (NDR) using an ALD deposited tunneling layer grown between 250 °C - 350 °C. A critical relationship between deposition temperature, oxygen vacancy concentration and room temperature NDR is presented. In this work, for a TiO2 deposition temperature of 250 °C, the peak NDR voltage position (Vpeak) and associated peak current density (Jpeak) are ∼4.3 V and −0.14 A/cm2, respectively, with a PVCR as high as 1.69 while operating at room temperature. The highest PVCR recorded was 4.89 ± 0.18 using an ALD deposition temperature of 350 °C. The key advantages of the ALD process used in fabrication of PTDs are increased repeatability and manufacturability.