Dopant Distribution in Ga‐Implanted CdO—A Correlative Microscopy and Molecular Dynamics Study

ABSTRACT

Focused ion beam (FIB)‐induced site‐specific implantation is a favorable patterning technology that enables the modification of optical and electrical properties of semiconductors by directly writing ions into the structure with controlled spatial coherence. Here, 30 kV Ga ¹⁺ implantation is performed using a Ga‐sourced FIB into a 50 nm‐thick cadmium oxide (CdO) plasmonic thin film to achieve locally tunable mid‐infrared (MIR) plasmonic materials. A series of molecular dynamics (MD) simulations is first performed to analyze the Ga penetration depth into CdO as a function of the implantation offset angle. They show that offset angles greater than ∼5° result in dechanneling pathways. CdO films are Ga‐implanted over a similar angular range, and their transport properties are analyzed by Hall effect measurements. Following an activation anneal, all samples irradiated at 5° or more exhibit mobility values between 362 and 386 cm ² V ⁻¹ s ⁻¹ . To understand this trend, microstructural evolution as a function of offset angle is studied using scanning transmission electron microscope (STEM) and atom probe tomography (APT) for normal and 5° incidence irradiation. It is revealed that interfacial cluster formation is the determining factor for carrier mobility, where lower volume fraction and density are observed for inclined implantation.