Impurity Incorporation and Redistribution During the Growth of Single-Crystal Semiconductors by Molecular Beam Epitaxy: A Theoretical and Experimental Study

Experimental and theoretical results are presented for segregation of dopants in single-crystal semiconductors grown by molecular beam epitaxy (MBE). Experimental results include Sn doping of GaAs, Si doping of Ga(,x)Al(,x)As (where x ranges from 0 to 1), Zn-ion doping of GaAs, In doping of Si, and In and As ion doping of Si. The results demonstrate segregation of dopant atoms to the surface of growing epitaxial layers, low dopant incorporation probabilities during growth, transient doping level fluctuations resulting from growth parameter changes, and accelerated-beam doping effects. Increases, in excess of five orders of magnitude, in the incorporation probability of dopants were observed using accelerated-beams. In addition, accelerated-beam doping was shown to reduce dopant segregation and increase the dopant solid solubilities. A model describing the incorporation of dopants into MBE-grown single crystals is also presented. The model includes both thermodynamic and kinetic contributions and accounts for dopant adsorption and desorption from the surface, dopant segregation, diffusion, and film growth. The model correctly fits experimental results including those due to transient incorporation effects and accelerated-beam effects. Appendices describe the design and operation of a compact ion source for accelerated-beam doping, the engineering drawings of a MBE system built for the accelerated-beam studies, and the numerical methods and computer code used in the solution of the model equations.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Metallurgical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Rockett, Angus Alexander

• Engineering, Materials Science

Identifier

(UMI)AAI8711865

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71841