Optical and photoelectrochemical studies of GaAs and GaAIAs
Optical and photoelectrochemical studies of GaAs and GaAIAs
The electrochemical, photoelectrochemical and optical properties of bulk and epitaxial GaAs and Ga1-xAlxAs have been investigated under conditions of photodissolution. The samples had doping densities in the range 3x1017 - 2.2x1018 cm-3. A GaAs sample with a low defect density (< 104 cm-2) was also studied. The techniques used to investigate the samples included, capacitance measurements, impedance analysis, photocurrent spectroscopy, photocurrent voltammetry, electrolyte electroreflectance spectroscopy (EER), frequency resolved electrolyte electroreflectance spectroscopy (FREER) and intensity modulated photocurrent spectroscopy (IMPS). The results obtained by these methods show that the semiconductor/electrolyte interface is non-ideal. Mott-Schottky plots are non-linear and exhibit frequency dispersion both in the dark and under illumination. Photocurrent voltage curves show hysteresis and intensity dependent peaks in the photocurrent onset region. The potential distribution across the interface was analysed using a.c. impedance, EER, FREER and IMPS. The results show that the potential distribution depends upon pretreatment of the electrode as well as the potential and the illumination level. This is attributed to changes in the surface composition and to the effect of surface states. High rates of surface recombination were found after the electrochemical passivation of GaAlAs, suggesting that oxidation increases the surface state density and decreases the bandbending.
University of Southampton
1990
Hutton, Roger Stuart
(1990)
Optical and photoelectrochemical studies of GaAs and GaAIAs.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The electrochemical, photoelectrochemical and optical properties of bulk and epitaxial GaAs and Ga1-xAlxAs have been investigated under conditions of photodissolution. The samples had doping densities in the range 3x1017 - 2.2x1018 cm-3. A GaAs sample with a low defect density (< 104 cm-2) was also studied. The techniques used to investigate the samples included, capacitance measurements, impedance analysis, photocurrent spectroscopy, photocurrent voltammetry, electrolyte electroreflectance spectroscopy (EER), frequency resolved electrolyte electroreflectance spectroscopy (FREER) and intensity modulated photocurrent spectroscopy (IMPS). The results obtained by these methods show that the semiconductor/electrolyte interface is non-ideal. Mott-Schottky plots are non-linear and exhibit frequency dispersion both in the dark and under illumination. Photocurrent voltage curves show hysteresis and intensity dependent peaks in the photocurrent onset region. The potential distribution across the interface was analysed using a.c. impedance, EER, FREER and IMPS. The results show that the potential distribution depends upon pretreatment of the electrode as well as the potential and the illumination level. This is attributed to changes in the surface composition and to the effect of surface states. High rates of surface recombination were found after the electrochemical passivation of GaAlAs, suggesting that oxidation increases the surface state density and decreases the bandbending.
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Published date: 1990
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Local EPrints ID: 461804
URI: http://eprints.soton.ac.uk/id/eprint/461804
PURE UUID: 55fd7951-d68e-4562-bd75-2e9dba2d3c4e
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Date deposited: 04 Jul 2022 18:55
Last modified: 04 Jul 2022 18:55
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Author:
Roger Stuart Hutton
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