*Article* **Interface Optimization and Transport Modulation of Sm2O3/InP Metal Oxide Semiconductor Capacitors with Atomic Layer Deposition-Derived Laminated Interlayer**

**Jinyu Lu 1, Gang He 1,\*, Jin Yan 1, Zhenxiang Dai 2, Ganhong Zheng 1,\*, Shanshan Jiang 3, Lesheng Qiao 1, Qian Gao <sup>1</sup> and Zebo Fang 4,\***


**Abstract:** In this paper, the effect of atomic layer deposition-derived laminated interlayer on the interface chemistry and transport characteristics of sputtering-deposited Sm2O3/InP gate stacks have been investigated systematically. Based on X-ray photoelectron spectroscopy (XPS) measurements, it can be noted that ALD-derived Al2O3 interface passivation layer significantly prevents the appearance of substrate diffusion oxides and substantially optimizes gate dielectric performance. The leakage current experimental results confirm that the Sm2O3/Al2O3/InP stacked gate dielectric structure exhibits a lower leakage current density than the other samples, reaching a value of 2.87 <sup>×</sup> <sup>10</sup>−<sup>6</sup> A/cm2. In addition, conductivity analysis shows that high-quality metal oxide semiconductor capacitors based on Sm2O3/Al2O3/InP gate stacks have the lowest interfacial density of states (*D*it) value of 1.05 <sup>×</sup> 1013 cm−<sup>2</sup> eV−1. The conduction mechanisms of the InP-based MOS capacitors at low temperatures are not yet known, and to further explore the electron transport in InP-based MOS capacitors with different stacked gate dielectric structures, we placed samples for leakage current measurements at low varying temperatures (77–227 K). Based on the measurement results, Sm2O3/Al2O3/InP stacked gate dielectric is a promising candidate for InP-based metal oxide semiconductor field-effect-transistor devices (MOSFET) in the future.

**Keywords:** MOS capacitors; Sm2O3 high-k gate dielectric; atomic layer deposition; conduction mechanisms; interface state density
