High mobility Si0.15Ge0.85 growth by using the molten target sputtering (MTS) within heteroepitaxy framework

Abstract

High-speed SiGe film is promising use in photonics and electronics technologies continue to replace Si-based devices. High mobility Si0.15 Ge0.85 film on sapphire was grown at 890 °C substrate temperature by using a conventional magnetron sputtering system within the heteroepitaxy framework. 890 °C substrate temperate is impractical for commercial device manufacturing due to long thermal soak, loading time, and costly process. To leverage the practical SiGe device applications, the Molten Target Sputtering (MTS) techniques is developed. The MTS is an economic and robust process from high flux density and liquid-state of molecules benefits. At 500 °C, the lowest substrate temperature, high mobility Si0.15Ge0.85 film with continues morphology and 99.7% majority-orientation were grown by using the MTS. The hall electron mobilities of the Si0.15Ge0.85 grown at 500 °C are 456 cm2V−1s−1 and 123.9 cm2V−1s−1 at 5.59 × 1018 cm3 and 3.5 × 1020 cm3 carrier concentration at 22.38 °C, respectively. The values are 550% higher hall electron mobilities than that of Si at equivalent carrier concentration and temperatures. We envision that the MTS is beneficial for the heteroepitaxy framework film growth that requires high substrate temperature to overcome the large lattice parameter mismatch between film and substrate.