@article{aboelfotoh_borek_narayan_2000, title={Microstructure and electrical resistivity of Cu and Cu3Ge thin films on Si1-xGex alloy layers}, volume={87}, ISSN={["0021-8979"]}, DOI={10.1063/1.371868}, abstractNote={We have studied the reaction between Cu and ε1-Cu3Ge thin films and Si1−xGex (x=0.5) alloy layers epitaxially grown on Si(100) in the temperature range of 250–400 °C. In this temperature range, Cu reacts with the alloy to form a Cu3Si1−xGex ternary phase with an ordered body-centered-cubic crystal structure, and no Ge segregation occurs during the reaction. Unlike ε1-Cu3Ge, the Cu3Si1−xGex films exhibit a high-room-temperature resistivity of ∼150 μΩ cm. However, the Cu3Si1−xGex phase is not observed when Ge is added to Cu to form ε1-Cu3Ge. In contrast to the results reported for films of ε1-Cu3Ge formed on Si(100) substrates, the outdiffusion of Si into the ε1-Cu3Ge films is found to be suppressed when the films are formed on Si0.5Ge0.5 layers at temperatures up to 500 °C, and their resistivity remains low (typically less than 10 μΩ cm at room temperature), indicating the increased stability of ε1-Cu3Ge on Si1−xGex alloys. Furthermore, the ε1-Cu3Ge films form a sharp interface with the Si0.5Ge0.5 layers. These results indicate that ε1-Cu3Ge is an attractive candidate for contacts to SiGe-based devices.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Aboelfotoh, MO and Borek, MA and Narayan, J}, year={2000}, month={Jan}, pages={365–368} }
 @article{aboelfotoh_borek_narayan_1999, title={Interaction of Cu and Cu3Ge thin films with Si1-xGex alloys}, volume={75}, ISSN={["0003-6951"]}, DOI={10.1063/1.124804}, abstractNote={The interaction of Cu and Cu3Ge thin films with Si1−xGex (x=0.5) alloy layers epitaxially grown on Si(100) has been studied in the temperature range of 250–400 °C. In this temperature range, Cu reacts with the alloy to form a Cu3(Si1−xGex) ternary phase with an ordered body-centered-cubic crystal structure. The Cu3(Si1−xGex) phase exhibits high-room-temperature (∼150 μΩ cm) and nonmetallic resistivity. However, this ternary phase is not observed and the diffusion of Cu into the alloy is suppressed when Cu is replaced by low resistivity (typically less than 10 μΩ cm at room temperature) ε1-Cu3Ge phase. In contrast to the results reported for films of ε1-Cu3Ge formed on Si(100), the outdiffusion of Si into the ε1-Cu3Ge films is found to be suppressed when the films are formed on Si0.5Ge0.5 layers, indicating the increased stability of ε1-Cu3Ge on Si1−xGex alloys compared to pure silicon.}, number={12}, journal={APPLIED PHYSICS LETTERS}, author={Aboelfotoh, MO and Borek, MA and Narayan, J}, year={1999}, month={Sep}, pages={1739–1741} }
 @article{aboelfotoh_borek_narayan_1999, title={Ohmic contact to p-type GaAs using Cu3Ge}, volume={75}, ISSN={["1077-3118"]}, DOI={10.1063/1.125505}, abstractNote={We have investigated ε1−Cu3Ge as an ohmic contact to p-type GaAs, and found that the ε1−Cu3Ge contact has a specific contact resistivity of 5×10−6 Ω cm2 on p-type GaAs with doping concentrations of ∼7×1018 cm−3. The ε1−Cu3Ge contact exhibits a planar and structurally abrupt interface with the GaAs, and no reaction between the contact metal and the GaAs is required for contact formation. The contact is electrically stable during annealing at temperatures up to 400 °C. It is suggested that Ge is incorporated into the GaAs as a p-type impurity resulting in a low contact resistivity. Furthermore, the addition of Ge to Cu to form ε1−Cu3Ge is found to impede the diffusion of Cu into the p-type GaAs. Along with the results reported for n-type GaAs, the present results indicate that ε1−Cu3Ge is an attractive candidate for ohmic contact formation on both n- and p-type GaAs.}, number={25}, journal={APPLIED PHYSICS LETTERS}, author={Aboelfotoh, MO and Borek, MA and Narayan, J}, year={1999}, month={Dec}, pages={3953–3955} }