Low‐Flicker‐Noise MoS ₂ Transistors Enabled by High‐ κ Rare‐Earth Oxychlorides for Mixed‐Signal Electronics

ABSTRACT

The trade‐off between gate dielectric constant and interface quality limits two‐dimensional (2D) analog and mixed‐signal electronics because trap‐mediated 1/ f noise from amorphous oxides degrades signal fidelity. Here, single‐crystalline rare‐earth oxychlorides (REOCl; LaOCl and GdOCl) are employed as Cl‐terminated crystalline high‐ κ dielectrics that form atomically abrupt van der Waals interfaces with MoS ₂ . MoS ₂ /REOCl transistors exhibit near‐thermal‐limit switching, with minimum one‐decade‐averaged subthreshold swings of 65.7 and 63.2 mV dec ⁻¹ for LaOCl and GdOCl, with ultralow hysteresis and suppressed low‐frequency noise. Carrier‐number‐fluctuation analysis of two independently measured devices per dielectric yields effective noise‐derived interface trap densities of 1.15–1.94 × 10 ¹⁰ cm ⁻² eV ⁻¹ , approaching the hexagonal boron nitride regime while retaining high‐ κ electrostatic coupling. Channel‐area‐scaled normalized 1/ f noise remains up to two orders of magnitude below amorphous SiO ₂ /Al ₂ O ₃ /HfO ₂ controls, with on‐state S _I / I _D ² reaching ∼10 ⁻¹⁰ Hz ⁻¹ . A Samsung 28 nm high‐ κ /metal‐gate reference process design kit sensitivity analysis, with only the flicker‐noise coefficient varied, indicates reduced voltage‐controlled oscillator phase noise and phase‐locked‐loop jitter and an effective‐number‐of‐bits improvement of up to 1.45 bits in passive noise‐shaping successive‐approximation‐register analog‐to‐digital converters. These results establish REOCl as a trap‐poor high‐ κ dielectric platform for low‐noise 2D electronics and illustrate the mixed‐signal relevance of reduced transistor flicker noise.