An Ultralow EOT Ge MOS Device With Tetragonal HfO₂ and High Quality Hf_{<italic>x</italic>}Ge_{<italic>y</italic>}O Interfacial Layer

Abstract

A Ge MOS device with an ultralow equivalent oxide thickness of ∼0.5 nm and acceptable leakage current of 0.5 A/cm 2 is presented in this paper. The superior characteristics can be attributed to a tetragonal HfO 2 with a higher k value (k ∼ 31) and comparable bandgap. In addition, a Ge MOS device with tetragonal phase HfO 2 (t-HfO 2 ) also shows a lower leakage current and better thermal stability. The mechanisms for t-HfO 2 formation may be explained by the little Ge diffusion from Ge substrate and oxygen deficiency, which are obtained by in situ interfacial layer (IL) formation and high-k processes. The IL with k ∼ 13 can be formed by in situ H 2 O plasma treatment. Moreover, a Ge MOS device with the IL grown by H 2 O plasma shows smaller interface trap density and hysteresis effects due to a high composition of Ge +4 .

Reliable resistive switching of epitaxial single crystalline cubic Y-HfO2 RRAMs with Si as bottom electrodes

“…It is known that the monoclinic phase is the most common phase for HfO 2 among all its polymorphs. However, with certain dopings like Zr, Y, Si and oxygen vacancies, the phase transition from monoclinic to tetragonal [32], or to cubic [28] or even to orthorhombic [33] could occurs. In our case, no XRD reflections of monoclinic (figure 2(b)) nor tetragonal (figure 2(c)) phase can be found, indicating that the ∼24% Y doping results in a pure cubic phase of YDH.…”

Development of a methodology for the extraction of BSIM3v3.2.2 parameters of Ge-channel MOSFETs and estimation of analog circuit performance

“…The model takes into account various physical effects noticed in today's MOS devices including short and narrow channel effects on threshold voltage, non-uniform doping effect (in both lateral and vertical directions), mobility reduction due to vertical field, velocity saturation, drain-induced barrier lowering DIBL, channel length modulation CLM, effect of substrate biasing, subthreshold conduction, source/drain parasitic resistance, and so on. In recent years, Ge channel has been the focus of research for high-performance of pMOSFETs, as Ge exhibits record high hole mobility in all materials (Yu et al 2015;Fu et al 2014;Zhang et al 2013;Daele et al 2011;Mitard et al 2008;Biswas 2012, 2013a;Shin et al 2014;Yamamoto et al 2007). The outstanding hole transport property is exploited to fabricate high performance Ge channel p-MOSFETs so as to obtain high frequency analog, and fast switching logic circuit performance.…”