Exploring Heterointerface Characteristics and Charge-Storage Dynamics in ALD-Developed Ultra-Thin TiO2-In2O3/Au Heterojunctions

Abstract

Directional ionic migration in ultra-thin metal-oxide semiconductors under applied electric fields is a key mechanism for developing various electronic nanodevices. However, understanding charge transfer dynamics is challenging due to rapid ionic migration and uncontrolled charge transfer, which can reduce the functionality of microelectronic devices. This research investigates the supercapacitive-coupled memristive characteristics of ultra-thin heterostructured metal-oxide semiconductor films at TiO2-In2O3/Au Schottky junctions. Using atomic layer deposition (ALD), we nano-engineered In2O3/Au-based metal/semiconductor heterointerfaces. TEM studies followed by XPS elemental analysis revealed the chemical and structural characteristics of the heterointerfaces. Subsequent AFM studies of the hybrid heterointerfaces demonstrated supercapacitor-like behavior in nanometer-thick TiO2-In2O3/Au junctions, resembling ultra-thin supercapacitors, pseudocapacitors, and nanobatteries. The highest specific capacitance of 2.6 × 104 F.g−1 was measured in the TiO2-In2O3/Au junctions with an amorphous In2O3 electron gate. Additionally, we examined the impact of crystallization, finding that thermal annealing led to the formation of crystalline In2O3 films with higher oxygen vacancy content at TiO2-In2O3 heterointerfaces. This crystallization process resulted in the evolution of non-zero I-V hysteresis loops into zero I-V hysteresis loops with supercapacitive-coupled memristive characteristics. This research provides a platform for understanding and designing adjustable ultra-thin Schottky junctions with versatile electronic properties.