Mousley, Philip (2017) Growth and structural characterisation of spintronic thin films deposited onto III-V semiconductors. PhD thesis, University of Warwick.

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Abstract

A surface x-ray diffraction (SXRD) study has been conducted investigating the structural properties of Sb thin-film deposition onto InAs(111)B-(1 1) surfaces via molecular beam epitaxy (MBE). It was found that epitaxy was not possible for deposition at high substrate temperatures ( 220 C), which instead resulted in substitution of the surface As atomic sites. Successful epitaxy required a combination of deposition at room temperature, followed by a short anneal using a substrate temperature of 200 C . An increase in film thickness was found to decrease the difference between the intra-bilayer and inter-bilayer distances within the Sb _lm.

MBE growth of MnSb onto In0:5 Ga0:5 As(111)A-(2 2) surfaces has been investigated, with a focus on the effect of substrate temperature (Tsub ) and flux ratio JSb=Mn on thin _lm growth. It was found that slightly different settings are required compared to growth on GaAs(111) substrates, with intermixing between the overlayer and substrate being observed on multiple samples.

A SXRD study comparing the growth of MnSb on GaAs(111)A and GaAs (111)B surfaces was conducted . Reflection high energy electron diffraction (RHEED) observations during deposition indicate early-stage layer-by-layer growth is only attainable on GaAs(111)A substrates. SXRD measurements confirmed that this difference in early-stage growth process affects the quality of the overall layer, even for thicker films.

A SXRD study of multi-layer heterostructure growth was conducted, focussing on the deposition of GaAs onto MnSb/Ga(In)As(111)A and MnSb/GaAs(001) virtual substrates. Despite poor surface, morphology, deposition of crytalline material was achieved. It was found that for (111)A virtual substrates a shift in the central n-MnSb layer was observed, which is attributed to the formation of MnAs at the MnSb surface. For the (001) virtual substrate 3D island growth was observed, and a plausible epitaxial relation between the MnSb(1101) and GaAs(001) surfaces is presented.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering
Library of Congress Subject Headings (LCSH):	Semiconductors, Thin films -- Growth, Thin films -- Structure, Spintronics
Official Date:	September 2017
Dates:	Date Event September 2017 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bell, Gavin R.
Extent:	xvi, 214 leaves : illustrations, charts
Language:	eng

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