Reduction of Charge Trapping in $\hbox{HfO}_{2}$  Film on Ge Substrates by Atomic Layer Deposition of Various Passivating Interfacial Layers

The dielectric performance and charge trapping properties of <formula formulatype="inline"><tex Notation="TeX">$ \hbox{HfO}_{2}$</tex></formula> on a Ge substrate with various passivating interfacial layers (PILs), such as <formula formulatype="inline"><tex Notation="TeX">$\hbox{SiO}_{x}\hbox{N}_{y}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX"> $\hbox{AlO}_{x}\hbox{N}_{y}$</tex></formula>, <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{x}\hbox{N}_{y}$</tex> </formula>, and <formula formulatype="inline"><tex Notation="TeX">$\hbox{LaO}_{x}\hbox{N}_{y}$</tex></formula>, are investigated. The large capacitance–voltage (<formula formulatype="inline"><tex Notation="TeX">$C$</tex></formula>– <formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula>) hysteresis of <formula formulatype="inline"><tex Notation="TeX">$ \hbox{HfO}_{2}$</tex></formula> on a Ge substrate (<formula formulatype="inline"><tex Notation="TeX">$\sim$</tex></formula>1500 mV) was not improved by inserting either <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{x}\hbox{N}_{y}$</tex></formula> or <formula formulatype="inline"><tex Notation="TeX">$\hbox{LaO}_{x}\hbox{N}_{y}$</tex></formula> PIL between the <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{2}$</tex></formula> and Ge substrates, while both <formula formulatype="inline"><tex Notation="TeX">$\hbox{SiO}_{x}\hbox{N}_{y}$</tex></formula> and <formula formulatype="inline"> <tex Notation="TeX">$\hbox{AlO}_{x}\hbox{N}_{y}$</tex></formula> PILs induced a noticeable reduction of <formula formulatype="inline"><tex Notation="TeX">$C$</tex></formula>–<formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula> hysteresis. As the PILs' thicknesses increased, the <formula formulatype="inline"><tex Notation="TeX">$C$</tex></formula>– <formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula> hysteresis of <formula formulatype="inline"><tex Notation="TeX">$ \hbox{HfO}_{2}$</tex></formula> with <formula formulatype="inline"><tex Notation="TeX">$\hbox{SiO}_{x}\hbox{N}_{y}$</tex></formula> PIL decreased to almost zero, while that of <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{2}$</tex></formula> with <formula formulatype="inline"><tex Notation="TeX">$\hbox{AlO}_{x}\hbox{N}_{y}$</tex></formula> PIL decreased but was saturated at approximately 400 mV. Furthermore, the charge trapping property of <formula formulatype="inline"><tex Notation="TeX">$ \hbox{HfO}_{2}$</tex></formula> with <formula formulatype="inline"><tex Notation="TeX">$\hbox{SiO}_{x}\hbox{N}_{y}$</tex></formula> PIL on a Ge substrate is comparable to that of <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{2}$</tex></formula> grown on a Si substrate. Negligible <formula formulatype="inline"><tex Notation="TeX">$C$</tex></formula>– <formula formulatype="inline"><tex Notation="TeX">$V$</tex></formula> hysteresis and negligible charge trapping of <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{2}$</tex></formula> with <formula formulatype="inline"><tex Notation="TeX">$ \hbox{SiO}_{x}\hbox{N}_{y}$</tex></formula> PIL were understood from the fact that <formula formulatype="inline"> <tex Notation="TeX">$\hbox{SiO}_{x}\hbox{N}_{y}$</tex></formula> is more resistant to react with a Ge substrate and defective Ge suboxides are efficiently suppressed during the formation of <formula formulatype="inline"><tex Notation="TeX">$\hbox{SiO}_{x} \hbox{N}_{y}$</tex></formula> PIL and <formula formulatype="inline"><tex Notation="TeX">$\hbox{HfO}_{2}$</tex></formula> layers.