Impact of Premetallization Surface Preparation on Nickel-based Ohmic Contacts to Germanium Telluride: An X-ray Photoelectron Spectroscopic Study.

Title Impact of Premetallization Surface Preparation on Nickel-based Ohmic Contacts to Germanium Telluride: An X-ray Photoelectron Spectroscopic Study.
Authors H.M. Aldosari; H. Simchi; Z. Ding; K.A. Cooley; S.Y. Yu; S.E. Mohney
Journal ACS Appl Mater Interfaces
DOI
Abstract

Surfaces of polycrystalline ?-GeTe films were studied by X-ray photoelectron spectroscopy (XPS) after different treatments in an effort to understand the effect of premetallization surface treatments on the resistance of Ni-based contacts to GeTe. UV-O3 is often used to remove organic contaminants after lithography and prior to metallization; therefore, UV-O3 treatment was used first for 10 min prior to ex situ treatments, which led to oxidation of both Ge and Te to GeOx (x < 2) and TeO2, respectively. Then the oxides were removed by deionized (DI) H2O, (NH4)2S, and HCl treatments. Additionally, in situ Ar(+) ion etching was used to clean the GeTe surface without prior UV-O3 treatment. Ar(+) ion etching, H2O, and (NH4)2S treatments create a surface richer in Ge compared to the HCl treatment, after which the surface is Te-rich. However, (NH4)2S also oxidizes Ge and gradually etches the GeTe film. All treated surfaces showed poor stability upon prolonged exposure to air, revealing that even (NH4)2S does not passivate the GeTe surface. The refined transfer length method (RTLM) was used to measure the contact resistance (Rc) of as-deposited Ni-based contacts to GeTe as a function of premetallization surface preparation. HCl-treated samples had the highest Rc (0.036 ± 0.002 ?·mm), which was more than twice that of the other surface treatments. This increase in Rc is attributed to formation of the Ni1.29Te phase at the Ni/GeTe interface due to an abundance of Te at the surface after HCl treatment. In general, treatments that resulted in Ge-rich surfaces offered lower Rc.

Citation H.M. Aldosari; H. Simchi; Z. Ding; K.A. Cooley; S.Y. Yu; S.E. Mohney.Impact of Premetallization Surface Preparation on Nickel-based Ohmic Contacts to Germanium Telluride: An X-ray Photoelectron Spectroscopic Study.. ACS Appl Mater Interfaces. 2016;8(50):3480234809. doi:

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Tellurium

See more Tellurium products. Tellurium (atomic symbol: Te, atomic number: 52) is a Block P, Group 16, Period 5 element with an atomic radius of 127.60. Tellurium Bohr ModelThe number of electrons in each of tellurium's shells is 2, 8, 18, 18, 6 and its electron configuration is [Kr] 4d10 5s2 5p4. Tellurium was discovered by Franz Muller von Reichenstein in 1782 and first isolated by Martin Heinrich Klaproth in 1798. In its elemental form, tellurium has a silvery lustrous gray appearance. The tellurium atom has a radius of 140 pm and a Van der Waals radius of 206 pm. Elemental TelluriumTellurium is most commonly sourced from the anode sludges produced as a byproduct of copper refining. The name Tellurium originates from the Greek word Tellus, meaning Earth.

Nickel

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Germanium

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