Fermi-level depinning in metal/Ge interface using oxygen plasma treatment

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Oxygen (O<SUB>2</SUB>) plasma treatment on germanium (Ge) surface was employed to depin Fermi-level in Al/n-type Ge interface. The Al contact to n-type Ge without and with O<SUB>2</SUB> plasma treatments for 1 and 2 min showed rectifying characteristics despite the low work function of Al, which could be associated with the Fermi-level pinning. An increase in O<SUB>2</SUB> plasma treatment time resulted in a decrease in Schottky barrier height along with the improvement of the homogeneity of Schottky interface. On the other hand, Al contact to O<SUB>2</SUB> plasma-treated n-type Ge for 3 min exhibited Ohmic behavior, implying the depinning of Fermi-level in Al/n-type Ge interface. A transition from rectifying to Ohmic behavior observed in Al/n-type Ge contact with O<SUB>2</SUB> plasma treatment for 3 min could be attributed to the more homogenous and stoichiometric formation of Ge-oxide layer. Such a high quality Ge-oxide layer effectively passivated unsatisfied surface states in Ge, which could be responsible for Fermi-level depinning of Ge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> O<SUB>2</SUB> plasma treatment on Ge surface was employed to depin Fermi-level of Ge interface. </LI> <LI> Transition from Schottky to Ohmic behavior was observed in Al/n-type Ge with O<SUB>2</SUB> plasma treatment for 3 min. </LI> <LI> An increase in O<SUB>2</SUB> plasma treatment time led to the improved homogeneity of Schottky interface. </LI> <LI> More homogenous and stoichiometric Ge-oxide layer was formed after O<SUB>2</SUB> plasma treatment for 3 min. </LI> <LI> Ge surface passivation through Ge-oxide layer could be a main cause of depinning the Fermi-level of Ge. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>