Silicon; Scanning tunneling microscopy (STM); Amorphous semiconductors; Surface structure; Hydrogen additions; Chemical vapor deposition (CVD); Thin films
A scanning tunneling microscope has been used to study the topography of the as-grown surface of device-quality, intrinsic, hydrogenated amorphous silicon deposited by rf discharge from silane. The substrates were atomically flat, oxide-free, single-crystal silicon or gallium arsenide. No evidence for island formation or nanoscale irregularities was seen in studies of 100-Å-thick films on either silicon or gallium arsenide. The topography of 1000- and 4000-Å-thick films has much variation; many regions can be characterized as "rolling hills," but atomically flat areas have also been observed nearby. Generally, it appears that surface diffusion plays a role in smoothing the film topography. In most regions, the observed slopes were 10% or less from horizontal, but some steep-sided valleys, indicating incipient voids, were observed. The effect of the finite size of the scanning tunneling microscope probe tip is considered; this has an effect on the observed images in some cases.
© 1993 David M. Tanenbaum
The following article appeared in "Nanoscale study of the as-grown hydrogenated amorphous silicon surface," G. C. Stutzin, R. M. Ostrom, Alan Gallagher, and D. M. Tanenbaum, J. Appl. Phys. 74, 91 (1993), DOI:10.1063/1.355203 and may be found at http://link.aip.org/link/?JAPIAU/74/91/1