Improved Performance of MoS2 Negative-Capacitance Field-Effect Transistors With Hf1–xLaxOyNz as Gate Dielectric by Optimizing La Content and Anneal Temperature Plus NH3-Plasma Treatment
Improved Performance of MoS2 Negative-Capacitance Field-Effect Transistors With Hf1–xLaxOyNz as Gate Dielectric by Optimizing La Content and Anneal Temperature Plus NH3-Plasma Treatment
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DOI：
10.1109/ted.2023.3299914
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发表时间：
2023-10
影响因子：
3.1
通讯作者：
Yuying Tian;Lu Liu;Weichao Jiang;Jingping Xu
中科院分区：
文献类型：
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作者：
Yuying Tian;Lu Liu;Weichao Jiang;Jingping Xu
采用共溅射镧掺杂的铌基氮氧化物（HfLaON）作为铁电栅介质，以二硫化钼（MoS 2）为沟道，制备了负电容场效应晶体管（NCFET）。通过对薄膜的微观分析和电学特性的表征，证实了HfLaON薄膜的铁电性。研究了La含量和退火温度对薄膜铁电性和MoS_2 NCF薄膜电性能的影响。结果表明，当La含量为10%、退火温度为800 °C时，样品的亚阈值摆幅（SS = 44.5mV/dec）和磁滞回线（94.4mV）均较低，这是由于样品中形成了更多的正交相，从而提高了样品的铁电性。此外，远程NH3-等离子体处理用于改善HfLaON薄膜的质量和器件的电性能，这导致与没有NH3-等离子体处理的器件相比，更低的SS（38.2 mV/dec）、更小的滞后（54.7 mV）和更高的开/关电流比（1.57 $\× 1，10 ^{6}$）。其机理在于N的掺入可以钝化氧空位和悬空键，降低薄膜表面粗糙度，从而改善薄膜及其界面的质量，提高薄膜的铁电性，从而增强NCF薄膜的负电容（NC）效应。
A negative-capacitance field-effect transistor (NCFET) is fabricated by co-sputtering lanthanum (La)-doped hafnium-based oxynitride (HfLaON) as ferroelectric gate dielectric and using MoS2 as the channel. The ferroelectricity of the HfLaON thin films is verified through microanalyses on the thin film and electrical characterization. Effects of La content and anneal temperature on the ferroelectricity of the thin films and electrical properties of MoS2 NCFETs are investigated. It is found that a low subthreshold swing (SS = 44.5 mV/dec) and small hysteresis (94.4 mV) can be achieved when the La content and anneal temperature are 10% and 800 °C respectively, due to the formation of more orthorhombic phases and thus enhanced ferroelectricity. Further, a remote NH3-plasma treatment is used to improve the quality of the HfLaON thin film and electrical properties of the devices, which results in a lower SS (38.2 mV/dec), a smaller hysteresis (54.7 mV), and a higher ON/ OFF current ratio (1.57 $\times \,\,10^{{6}}$ ) than that of the device without NH3-plasma treatment. The involved mechanisms lie in the fact the N incorporation into the thin film could improve the qualities of the thin film and its interfaces by passivating oxygen vacancies and dangling bonds, and reducing its surface roughness, which enhances the ferroelectricity of the thin films and thus negative-capacitance (NC) effect of NCFETs.