Interface Chemistry and Defect State Optimization of the ErSmO/InP Heterojunction Modified by ALD-Driven Al₂O₃ Interlayers

In this work, the effects of the atomic-layer deposition (ALD)-derived Al 2 O 3 passivation layer with different growth cycles on the interfacial chemistry and electrical performance of sputtering-driven ErSmO/InP metal oxide semiconductor (MOS) capacitors have been comparatively investigated. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization have confirmed that the ALD-driven Al 2 O 3 passivation layer with 20 growth cycles could form a flat dielectric layer and effectively suppress the diffusion of In and P elements at the InP interface. Meanwhile, the ErSmO/Al 2 O 3 /InP gate stack with 20 growth cycles exhibited optimal electrical properties, including a large dielectric constant of 37.42, a minimum interface state density ( D it ) of 5.43 × 10 11 eV –1 cm –2, and a low leakage current of 3.95 × 10 –6 A/cm –2 . The leakage current conduction mechanisms of InP-MOS capacitors measured at room temperature and low temperature have also been systematically analyzed. Particularly, low-frequency noise (LFN) is used to evaluate trap levels in InP-MOS capacitors. All experimental results have demonstrated that the ErSmO/Al 2 O 3 /InP gate stack has potential applications in future ultrahigh-speed and high-frequency microelectronic devices.