Silicon epitaxy on H-terminated Si (100) surfaces at 250°C

[Display omitted] •Demonstration of epitaxial Si growth on H: Si and Si up to 25nm thickness while limiting the temperature to 250°C.•STM analysis and cross section TEM provide direct atomic resolution evidence revealing the nature and quality of epitaxy.•Epitaxial growth from sub-monolayer to 25nm thickness at relatively higher flux rates.•Growth parameters optimized to achieve high quality epitaxy required for atomic scale device fabrication. Low temperature Si epitaxy has become increasingly important due to its critical role in the encapsulation and performance of buried nanoscale dopant devices. We demonstrate epitaxial growth up to nominally 25nm, at 250°C, with analysis at successive growth steps using STM and cross section TEM to reveal the nature and quality of the epitaxial growth. STM images indicate that growth morphology of both Si on Si and Si on H-terminated Si (H: Si) is epitaxial in nature at temperatures as low as 250°C. For Si on Si growth at 250°C, we show that the Si epitaxial growth front maintains a constant morphology after reaching a specific thickness threshold. Although the in-plane mobility of silicon is affected on the H: Si surface due to the presence of H atoms during initial sub-monolayer growth, STM images reveal long range order and demonstrate that growth proceeds by epitaxial island growth albeit with noticeable surface roughening.