Observation of Controllable Negative Differential Resistance Behaviors through Morphology-Dependent Zinc Oxide/p-Si Heterointerface Structures

Negative differential resistance (NDR) has received considerable attention owing to the unique switching property, which exhibits an n-shaped current-voltage curve without a monolithic increase in current as of the applied voltage bias increases. Nevertheless, various issues in previously reported NDR devices need to be addressed, such as complex manufacturing processes, operational instability, and difficulties in large-area processing. In addition, methods for generating and controlling NDR have not yet been developed. This paper presents the findings of morphology-dependent NDR in which three types of zinc oxide (ZnO) build a junction with p-Si in the form of small nanoparticles, large nanoparticles, and films. The principle of NDR behaviors is elucidated through a comprehensive study, including an analysis of the energy band structure, morphological investigation, and electrical characterization, offering control of the peak-to-valley current ratio (PVCR). The highest PVCR = 4.96 A A(-1) is obtained in the quantum dot ZnO/p-Si structure and the NDR characteristics occur without external stimuli, such as irradiating light, cryogenic temperatures, or controlled atmospheres.