The growth and structure of semiconducting thin films

Abstract

I n this review silicon and gallium arsenide are considered as typical examples of elemental and compound semiconductors respectively, and an account is given of the nucleation, growth and structure, both crystallographic and electrical, of autoepitaxial films of these materials. Some discussion of preparative techniques is first provided to illustrate the basic principles of thin film growth, but experimental details are not included. T h e use of modern methods of surface physics to assess the influence of the substrate surface on nucleation and subsequent growth behaviour is discussed, particularly with reference to results obtained using low energy electron diffraction, Auger electron spectroscopy and molecular beam techniques. Finally, the way in which studies of autoepitaxial growth have been extended to include growth on other substrates is considered.

Chemical Vapor Deposition of Epitaxial Silicon from Silane at Low Temperatures: I . Very Low Pressure Deposition

“…Some researchers have measured silane reaction rates and silicon deposition rates which indicate first-order reaction kinetics for the surface controlled deposition reactions (10)(11)(12). Others have reported sublinear silane reaction orders (13)(14)(15)(16))/This is especially evident for studies at temperatures below 650~ Early experimental work for epitaxial silicon depositions exhibited silane reaction orders of nearly two, but this has since been attributed to complications due to surface contamination and/or homogeneous chemistry effects (17). Many of these results have been measured under nominally identical reactor conditions and the disparate conclusions lead to significant confusion regarding interpretation.…”

How does your crystal grow? A commentary on Burton, Cabrera and Frank (1951) ‘The growth of crystals and the equilibrium structure of their surfaces’

“…MBE is an ultra-high-vacuum (UHV) technique in which controlled growth of ultrathin films of high perfection can be achieved, particularly valuable for the fabrication of modern semiconductor devices (e.g. [32][33][34]) including not only two-dimensional films but also one-dimensional wires and (nominally) zero-dimensional 'dots'. The fact that such crystals may be free of dislocations clearly implies that spiral growth at screw dislocations does not play a role, and in general the growth is based on the generation of single-layer height two-dimensional nuclei followed by lateral expansion of these layers by step-edge growth until each layer is completed.…”

Progressive growth rate reduction due to impurity desorption in vapor grown hexamethylenetetramine crystals

“…It was thus found that in 100 hrs (approximate duration of a ( ) S A n t -measurement run) the background impurity level due to ampoule degassing did not exceed 1% of the HMT sublimation pressure. The volatile impurities produced by sealing-off procedures were very likely the background traces usually associated to a technical vacuum (10 -5 ÷10 -6 mbar), typically light-mass species such as H 2 O, CO 2 , N 2 , Ar , H 2 and some hydrocarbons [7]. As it was now evident that the residual volatile impurities during a CPVT growth process were the result of continuous desorption from the source, a further purification stage was considered, in which HMT fractions were sublimed and re-crystallized under dynamic vacuum at low temperature and low pumping rate.…”