Image of the Month

July 2016

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

Figure 1:  Empty states STM images of 0.4 ML Si deposition on bare Si (100) surface at 250 C (deposition rate is 0.4 ML/min) and H terminated at 140 ◦C. (Applied Surface Science 378 (2016) 301–307)

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 25 nm, at 250C, 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 250C. For Si on Si growth at 250C, 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.

Credits:
Xiao Deng1,2, Pradeep Namboodiri2,, Kai Li2, Xiqiao Wang2,3, Gheorghe Stan2, Alline F. Myers2, Xinbin Cheng1, Tongbao Li1, Richard M. Silver2

1 School of Physics Science and Engineering, Tongji University, Shanghai 200092, People’s Republic of Chinab

2 National Institute of Standards and Technology, Gaithersburg, MD 20899, United States

3 University of Maryland, College Park, MD 20740, United States

Images and data graciously provided by Pradeep Namboodiri, NIST, Gaithersburg, Maryland.

Microscope:
RHK PanScan Microscope

Control System:
RHK R9 Control System