The early stages of CdTe epitaxial growth on gold single crystal electrode surfaces
The early stages of CdTe epitaxial growth on gold single crystal electrode surfaces
In this dissertation an investigation into the initial phases of epitaxial CdTe monolayer film growth onto the low index planes of gold employing in-situ scanning tunnelling microscopy (STM) is presented. The CdTe films were grown by the sequential deposition of a partial monolayer of Te and Cd at underpotentials using Electrochemical Atomic Layer Epitaxy (ECALE). Atomic resolution images of the first UPD structures of tellurium prior to Cd deposition have been obtained in a CdSO4 solution indicating the stability of these adlayers towards emersion from solution. A new Te UPD structure could be imaged on the Au(111) surface under these conditions which could not be observed in previous ex-situ and in-situ studies. This exhibited a characteristic row morphology with long range ordering and could be identified as having a (3x9) unit cell registry with the underlying Au(111) substrate.
The CdTe films were found to grow two-dimensionally in a layer-by-layer fashion. On the basis of detailed potential step experiments a refined mechanism for the observed structural transition from an initial (2x2) Te overlayer to a c(2x2) structure upon Cd UPD on the Au(100) surface is proposed, which has so far been a matter of some controversy in the literature. Atomically resolved STM images on the Au (111) and Au(110) plane revealed well-ordered CdTe structures with hexagonal symmetry. The adlayer unit cells were found to be consistent with a (3x3) and a (2x3) overlayer structure. The kinetics of CdTe electrocrystallization were studied by performing scan rate dependent cyclic voltammetry experiments. An analysis of this cyclic voltammetry data suggested that the Cd monolayer formation and dissolution Te modified gold surfaces proceeds by an instantaneous two-dimensional nucleation and growth mechanism.
The results of an in-situ STM study in combination with ultra-high vacuum (UHV) electrochemical transfer experiments using x-ray photoelectron spectroscopy (XPS) and low-energy diffraction (LEED) on underpotentially deposited tellurium layers on Au(hkl) are also reported.
University of Southampton
1997
Nandhakumar, Iris Schulz
(1997)
The early stages of CdTe epitaxial growth on gold single crystal electrode surfaces.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In this dissertation an investigation into the initial phases of epitaxial CdTe monolayer film growth onto the low index planes of gold employing in-situ scanning tunnelling microscopy (STM) is presented. The CdTe films were grown by the sequential deposition of a partial monolayer of Te and Cd at underpotentials using Electrochemical Atomic Layer Epitaxy (ECALE). Atomic resolution images of the first UPD structures of tellurium prior to Cd deposition have been obtained in a CdSO4 solution indicating the stability of these adlayers towards emersion from solution. A new Te UPD structure could be imaged on the Au(111) surface under these conditions which could not be observed in previous ex-situ and in-situ studies. This exhibited a characteristic row morphology with long range ordering and could be identified as having a (3x9) unit cell registry with the underlying Au(111) substrate.
The CdTe films were found to grow two-dimensionally in a layer-by-layer fashion. On the basis of detailed potential step experiments a refined mechanism for the observed structural transition from an initial (2x2) Te overlayer to a c(2x2) structure upon Cd UPD on the Au(100) surface is proposed, which has so far been a matter of some controversy in the literature. Atomically resolved STM images on the Au (111) and Au(110) plane revealed well-ordered CdTe structures with hexagonal symmetry. The adlayer unit cells were found to be consistent with a (3x3) and a (2x3) overlayer structure. The kinetics of CdTe electrocrystallization were studied by performing scan rate dependent cyclic voltammetry experiments. An analysis of this cyclic voltammetry data suggested that the Cd monolayer formation and dissolution Te modified gold surfaces proceeds by an instantaneous two-dimensional nucleation and growth mechanism.
The results of an in-situ STM study in combination with ultra-high vacuum (UHV) electrochemical transfer experiments using x-ray photoelectron spectroscopy (XPS) and low-energy diffraction (LEED) on underpotentially deposited tellurium layers on Au(hkl) are also reported.
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Published date: 1997
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Local EPrints ID: 463126
URI: http://eprints.soton.ac.uk/id/eprint/463126
PURE UUID: 048a4654-06b7-47cd-a77d-e626126c6eeb
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Date deposited: 04 Jul 2022 20:45
Last modified: 04 Jul 2022 20:45
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Author:
Iris Schulz Nandhakumar
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