Ismail Musa - Academia.edu (original) (raw)
Papers by Ismail Musa
IOCMA 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Chemical Society of Nigeria
New solid-state metal complex of Fe (II) with paracetamol (ligand), that is, [Fe(para)2Cl2] were ... more New solid-state metal complex of Fe (II) with paracetamol (ligand), that is, [Fe(para)2Cl2] were synthesized mechanically in 1:2 ratio. The complex has been characterized using physicochemical properties and spectral studies. From the IR and electronic spectral studies, the spectra of the complex were different from that of ligand suggesting the formation of coordination compound. Paracetamol was found to be bidentate ligand in which Fe (II) ion coordinated through the oxygen atom of carbonyl of ketone and nitrogen atom of amide in which the complex is assumed to have octahedral geometry. The complex has shown good antimicrobial activities. The solid-state synthetic method is quick and gives a higher yield, without the need of solvent or heating. Its present higher efficiency in terms of materials, time and energy compared to solution-based synthesis. It is therefore, recommended among others that, solid-state synthesis method should be used in the synthesizing drugs with metals.
![Research paper thumbnail of Genetic variability and trait correlation studies in okra [Abelmoschus esculentus (L.) Moench]](https://attachments.academia-assets.com/117238979/thumbnails/1.jpg)
](Agriculture and Biology Journal of North America, 2013
Okra fruit/pod is one of the widely consumed vegetable in sub-tropical part of the world. In Nige... more Okra fruit/pod is one of the widely consumed vegetable in sub-tropical part of the world. In Nigeria, there are several yield and production challenges involving the cultivation of poor genotypes. In this study, field trials were carried out for local Okra cultivar in two locations within the Savannah agro ecological zone of Nigeria during the 2011/2012 cropping season to evaluate the extend of variability and character association in some selected quantitative traits. The result reveals wide variability in some yield traits, with growth contributing factors playing significant role within the two locations. A strong genotype-environment interaction affecting the yield performance of the local cultivar was also observed.
Journal of Applied Sciences and Environmental Management, 2019
Urban flooding has become a monumental yearly disaster in many of the world’s cities and Gombe to... more Urban flooding has become a monumental yearly disaster in many of the world’s cities and Gombe town in particular. This paper focused on some hydro-geomorphological characteristics that influence flooding in Gombe town. Statistical methods and geographic information techniques were used for the assessment. The result revealed that the highest API of 166.62 mm occurred on the 5/9/2014. The rainfall amount was 92.5mm for a duration 48 minutes, average rainfall intensity was 115.63, stage height (1.42m), average flow velocity (0.98m/s), and instantaneous discharge of 9.47m3 /s. This corresponds with the flood disaster that occurred in Gombe town on the same date (5/9/2014). On the other hand, the least API of 18.12 mm occurred on the 18/6/2014. The rainfall amount was 1.2mm for 62 minutes, average rainfall intensity was 1.16, stage height (0.30m), average flow velocity (0.24m/s), and instantaneous discharge of 0.49m3 /s. findings also showed that very steep slope covered 2.4537km2 (1.7...
IOP Conference Series: Materials Science and Engineering, 2018
Current supply chain management (SCM) has become a potentially treasured way of safeguarding comp... more Current supply chain management (SCM) has become a potentially treasured way of safeguarding competitive advantage and improving organizational performance since competition is no longer between organizations, but among supply chains. This research conceptualizes and develops four resiliency practices (Flexibility, Redundancy, Collaboration and Agility) and tests the relationships between organizations' financial performance and competitive advantage in manufacturing firms. The study involves manufacturing firms in Indonesia and Sierra Leone. The study used stratified random sampling to pick a sample size of 95 manufacturing firms, which represented different industrial sectors. The respondents were mainly managers of different manufacturing companies. The relationships proposed in the conceptual framework were tested using correlation analysis. The results indicate that higher levels of resilience practices in manufacturing firms can lead to enhanced competitive advantage and improved financial performance.
International Journal for Research in Applied Science and Engineering Technology, 2019
Proper assessment of water quality status in a river system is an essential task for meeting the ... more Proper assessment of water quality status in a river system is an essential task for meeting the goals of environmental management basin. However, a discrepancy frequently arises from the lack of a clear distinction between each water utilization mode, the uncertainty in the quality criteria of water employed and vagueness or fuzziness embedded in the decision making output values. Owing to inherent imprecision, difficulties always exist in some conventional methodologies like water quality index (WQI) when describing integrated water quality conditions with respect to various chemical constituents, biological aspects, nutrients, and aesthetic qualities such as Dissolved Oxygen (D.O.), Biochemical Oxygen Demand (B.O.D.), Temperature, Therefore, in this study, a methodology based on Fuzzy Inference Systems (FIS) would be use to assess water quality of water under the study.
Asian Research Journal of Mathematics, 2019
Presented here is a numerical integrator, with sixth order of convergence, for solving oscillator... more Presented here is a numerical integrator, with sixth order of convergence, for solving oscillatory problems. Dispersion and dissipation errors are taken into account in the course of deriving the method. As a result, the method possesses dissipation of order infinity and dispersive of order six. Validity and effectiveness of the method are tested on a number of test problems. Results obtained show that the new method is better than its equals in the scientific literature.
Nature, 1998
Field-emission displays contain materials that emit electrons when charged to a low (negative) po... more Field-emission displays contain materials that emit electrons when charged to a low (negative) potential; the electrons excite light emission from phosphor screens. These devices have the potential to provide flat-panel visual displays with good picture quality at low ...
Age and Ageing, 2015
Background: advance care planning (ACP) is a process to establish an individual's preference for ... more Background: advance care planning (ACP) is a process to establish an individual's preference for care in the future; few UK studies have been conducted to ascertain public attitudes towards ACP. Objective: the aim of this study was to assess the attitudes of older people in East Midlands through the development and administration of a survey. Design: the survey questionnaire was developed on the basis of a literature review, exploratory focus groups with older adults and expert advisor input. The final questions were then re-tested with lay volunteers. Setting: thirteen general practices were enrolled to send out surveys to potential participants aged 65 or older. There were no additional inclusion or exclusion criteria for participants. Methods: simple descriptive statistics were used to describe the responses and regression analyses were used to evaluate which items predicted responses to key outcomes. Results: of the 5,375 (34%) community-dwelling older peoples, 1,823 returned questionnaires. Seventeen per cent of respondents had prepared an ACP document; of whom, 4% had completed an Advance Decision to Refuse Treatment (ADRT). Five per cent of respondents stated that they had been offered an opportunity to talk about ACP. Predictors of completing an ACP document included: being offered the opportunity to discuss ACP, older age, better physical function and male gender. Levels of trust were higher for families than for professionals. One-third of the respondents would be interested in talking about ACP if sessions were available. Conclusion: although a third of the respondents were in favour of discussing ACP if the opportunity was available with their GP, only a relative minority (17%) had actively engaged. Preferences were for informal discussions with family rather than professionals.
Life-Cycle of Engineering Systems, 2016
International Electron Devices Meeting 1998. Technical Digest (Cat. No.98CH36217)
There is a need for low cost, efficient field emission materials for use in flat panel displays. ... more There is a need for low cost, efficient field emission materials for use in flat panel displays. The discovery, by the authors, of high emission currents from `spin-on' materials, consisting of conjugated polymers, is, therefore, of potential importance. Analysis based on the presence of space charge limited currents in the polymer films is described and comparison is made with measurement
Life-Cycle of Civil Engineering Systems, 2014
Stress concentration factor (SCF) analysis is carried out for welded T-joints made up of steel ci... more Stress concentration factor (SCF) analysis is carried out for welded T-joints made up of steel circular hollow section brace welded onto concrete-filled circular hollow section chord. A finite element model has been developed employing ABAQUS software to simulate the performance of T-joints with concrete-filled chords under axial force on the brace. Modelling of the weld profile has been included in the simulation. An 8-node 3D hexahedral solid element with full integration scheme has been employed in the simulation. The interaction between the chord and concrete filling has been assumed to be due to friction only. The hot spot stresses have been obtained by linear extrapolation of the stresses in the region recommended by CIDECT. The outcome of the numerical simulation is verified using existing experimental results obtained by Wang et al. (2013)
MRS Proceedings, 1999
ABSTRACTCarbon based materials are considered to be amongst the most promising field emitters for... more ABSTRACTCarbon based materials are considered to be amongst the most promising field emitters for use in displays. Semiconducting polymer (regioregular poly3 octylthiophene) has been found by the authors to have the lowest threshold field reported to date for any carbon based material. The emission process is, we believe, associated with surface irregularities, voids, possibly resulting from solvent evaporation. Field intensification occurs, and as a consequence there is field emission from the top ridges of the voids. The current flowing through these regions is controlled by space charge in traps in the upper half of the energy gap. There is, in addition, current injected from the base of the voids and the two currents mix to give field emission with current IαV1.8 where V is the anode voltage. Measurements on capacitor samples using Aluminium, Gold and Calcium electrodes have been used to examine the conduction processes in the material and these are linked to results of field em...
Environment and Pollution, 2014
Thin Solid Films, 2011
Polyfluorene (PF) and its derivatives are very promising candidates for organic light emitting di... more Polyfluorene (PF) and its derivatives are very promising candidates for organic light emitting diodes (OLEDs) in lighting applications because of their high photoluminescence and electroluminescence efficiencies. Recent investigations of potential materials for OLEDs have shown that introducing n-type inorganic nanoparticles into conjugated polymers is efficient to produce stable and high performance devices. In this study, composite thin films made by incorporation of zinc oxide (ZnO) nanoparticles into a PF derivative have been prepared and their optical properties have been investigated. The prepared thin films were stored in different media (in air, in vacuum, in the dark or exposed to light) in order to study environmental influences on the material stability. Analysis of spectral data obtained from infrared (IR), Raman, UV-vis, and photoluminescence (PL) measurements shows a large enhancement in luminescence for polymer nanocomposites while using high nanoparticle concentrations (within a limit of 10% ZnO). Time-resolved PL performed on those nanocomposite films corroborated the above result: it indicated that the light-emission enhancement can be explained by efficient energy transfer from nanoparticles to the polymer chains and increase of the chain separation distance. In addition, the nanocomposites were found to be more stable than pristine polymer films whatever the storage conditions were used. It was confirmed by IR analysis that incorporation of nanoparticles into polymers prohibited the formation of fluorenonyl groups in PF chains, which was identified as the main cause of the degradation of the polymer under photo-oxidation.
Synthetic Metals, 1998
Abstract The methods of reflection and transmission are used to determine the optical constants n... more Abstract The methods of reflection and transmission are used to determine the optical constants n and k of thin films of regioregular poly (3-octylthiophene). The technique is based on the simultaneous use of Fresnel laws and the dispersion relations between n and k of the film using an iterative process. The optical and Tauc gaps are also derived.
Journal of Applied Physics, 1997
We present an observation of extensive space-charge limited conduction in polybenzo[c]thiophene. ... more We present an observation of extensive space-charge limited conduction in polybenzo[c]thiophene. Strong evidence for the presence of three discrete trapping levels is shown with a possibility of a fourth trap level. The density of traps for the first three levels is found to be 5×1016 cm−3, 1×1017 cm−3, and 2×1017 cm−3, respectively. A lower limit for the free-carrier mobility was estimated to be ∼3×10−5 cm2 V−1 s−1.
Journal of Applied Physics, 1998
The temperature dependence of space-charge-limited currents in polybenzo[c]thiophene (PBCT) films... more The temperature dependence of space-charge-limited currents in polybenzo[c]thiophene (PBCT) films in a sandwich structure of aluminum/PBCT/indium–tin–oxide is presented. Free carrier space-charge-limited currents are identified and the free carrier mobility has been estimated to be ∼3×10−5 cm2 V−1 s−1. A trap of concentration ∼1.8×1017 cm−3 and energy ∼0.67 eV from the highest occupied molecular orbital level is estimated. The thickness dependence of the current, at constant voltage, is very close to that expected for a space-charge-limited mechanism. The Tauc band gap determined by optical spectrophotometry was found to be ∼1.34 eV.
Japanese Journal of Applied Physics, 1998
An investigation into the effect of carrier trapping in polymer Schottky diodes is presented. The... more An investigation into the effect of carrier trapping in polymer Schottky diodes is presented. The diodes have been fabricated using regioregular poly(3-octylthiophene) as the semiconductor and aluminium and indium doped tin-oxide as the rectifying and ohmic contacts respectively. The diodes show rectification ratios up to 3–4 orders of magnitude. Evidence for image-force lowering of the Schottky barrier is observed. The frequency dependence of the capacitance, conductance and dielectric loss is analysed, from which detailed information on the metal/semiconductor interface and the doping level is obtained. An equivalent circuit is proposed.
IOCMA 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of Chemical Society of Nigeria
New solid-state metal complex of Fe (II) with paracetamol (ligand), that is, [Fe(para)2Cl2] were ... more New solid-state metal complex of Fe (II) with paracetamol (ligand), that is, [Fe(para)2Cl2] were synthesized mechanically in 1:2 ratio. The complex has been characterized using physicochemical properties and spectral studies. From the IR and electronic spectral studies, the spectra of the complex were different from that of ligand suggesting the formation of coordination compound. Paracetamol was found to be bidentate ligand in which Fe (II) ion coordinated through the oxygen atom of carbonyl of ketone and nitrogen atom of amide in which the complex is assumed to have octahedral geometry. The complex has shown good antimicrobial activities. The solid-state synthetic method is quick and gives a higher yield, without the need of solvent or heating. Its present higher efficiency in terms of materials, time and energy compared to solution-based synthesis. It is therefore, recommended among others that, solid-state synthesis method should be used in the synthesizing drugs with metals.
Agriculture and Biology Journal of North America, 2013
Okra fruit/pod is one of the widely consumed vegetable in sub-tropical part of the world. In Nige... more Okra fruit/pod is one of the widely consumed vegetable in sub-tropical part of the world. In Nigeria, there are several yield and production challenges involving the cultivation of poor genotypes. In this study, field trials were carried out for local Okra cultivar in two locations within the Savannah agro ecological zone of Nigeria during the 2011/2012 cropping season to evaluate the extend of variability and character association in some selected quantitative traits. The result reveals wide variability in some yield traits, with growth contributing factors playing significant role within the two locations. A strong genotype-environment interaction affecting the yield performance of the local cultivar was also observed.
Journal of Applied Sciences and Environmental Management, 2019
Urban flooding has become a monumental yearly disaster in many of the world’s cities and Gombe to... more Urban flooding has become a monumental yearly disaster in many of the world’s cities and Gombe town in particular. This paper focused on some hydro-geomorphological characteristics that influence flooding in Gombe town. Statistical methods and geographic information techniques were used for the assessment. The result revealed that the highest API of 166.62 mm occurred on the 5/9/2014. The rainfall amount was 92.5mm for a duration 48 minutes, average rainfall intensity was 115.63, stage height (1.42m), average flow velocity (0.98m/s), and instantaneous discharge of 9.47m3 /s. This corresponds with the flood disaster that occurred in Gombe town on the same date (5/9/2014). On the other hand, the least API of 18.12 mm occurred on the 18/6/2014. The rainfall amount was 1.2mm for 62 minutes, average rainfall intensity was 1.16, stage height (0.30m), average flow velocity (0.24m/s), and instantaneous discharge of 0.49m3 /s. findings also showed that very steep slope covered 2.4537km2 (1.7...
IOP Conference Series: Materials Science and Engineering, 2018
Current supply chain management (SCM) has become a potentially treasured way of safeguarding comp... more Current supply chain management (SCM) has become a potentially treasured way of safeguarding competitive advantage and improving organizational performance since competition is no longer between organizations, but among supply chains. This research conceptualizes and develops four resiliency practices (Flexibility, Redundancy, Collaboration and Agility) and tests the relationships between organizations' financial performance and competitive advantage in manufacturing firms. The study involves manufacturing firms in Indonesia and Sierra Leone. The study used stratified random sampling to pick a sample size of 95 manufacturing firms, which represented different industrial sectors. The respondents were mainly managers of different manufacturing companies. The relationships proposed in the conceptual framework were tested using correlation analysis. The results indicate that higher levels of resilience practices in manufacturing firms can lead to enhanced competitive advantage and improved financial performance.
International Journal for Research in Applied Science and Engineering Technology, 2019
Proper assessment of water quality status in a river system is an essential task for meeting the ... more Proper assessment of water quality status in a river system is an essential task for meeting the goals of environmental management basin. However, a discrepancy frequently arises from the lack of a clear distinction between each water utilization mode, the uncertainty in the quality criteria of water employed and vagueness or fuzziness embedded in the decision making output values. Owing to inherent imprecision, difficulties always exist in some conventional methodologies like water quality index (WQI) when describing integrated water quality conditions with respect to various chemical constituents, biological aspects, nutrients, and aesthetic qualities such as Dissolved Oxygen (D.O.), Biochemical Oxygen Demand (B.O.D.), Temperature, Therefore, in this study, a methodology based on Fuzzy Inference Systems (FIS) would be use to assess water quality of water under the study.
Asian Research Journal of Mathematics, 2019
Presented here is a numerical integrator, with sixth order of convergence, for solving oscillator... more Presented here is a numerical integrator, with sixth order of convergence, for solving oscillatory problems. Dispersion and dissipation errors are taken into account in the course of deriving the method. As a result, the method possesses dissipation of order infinity and dispersive of order six. Validity and effectiveness of the method are tested on a number of test problems. Results obtained show that the new method is better than its equals in the scientific literature.
Nature, 1998
Field-emission displays contain materials that emit electrons when charged to a low (negative) po... more Field-emission displays contain materials that emit electrons when charged to a low (negative) potential; the electrons excite light emission from phosphor screens. These devices have the potential to provide flat-panel visual displays with good picture quality at low ...
Age and Ageing, 2015
Background: advance care planning (ACP) is a process to establish an individual's preference for ... more Background: advance care planning (ACP) is a process to establish an individual's preference for care in the future; few UK studies have been conducted to ascertain public attitudes towards ACP. Objective: the aim of this study was to assess the attitudes of older people in East Midlands through the development and administration of a survey. Design: the survey questionnaire was developed on the basis of a literature review, exploratory focus groups with older adults and expert advisor input. The final questions were then re-tested with lay volunteers. Setting: thirteen general practices were enrolled to send out surveys to potential participants aged 65 or older. There were no additional inclusion or exclusion criteria for participants. Methods: simple descriptive statistics were used to describe the responses and regression analyses were used to evaluate which items predicted responses to key outcomes. Results: of the 5,375 (34%) community-dwelling older peoples, 1,823 returned questionnaires. Seventeen per cent of respondents had prepared an ACP document; of whom, 4% had completed an Advance Decision to Refuse Treatment (ADRT). Five per cent of respondents stated that they had been offered an opportunity to talk about ACP. Predictors of completing an ACP document included: being offered the opportunity to discuss ACP, older age, better physical function and male gender. Levels of trust were higher for families than for professionals. One-third of the respondents would be interested in talking about ACP if sessions were available. Conclusion: although a third of the respondents were in favour of discussing ACP if the opportunity was available with their GP, only a relative minority (17%) had actively engaged. Preferences were for informal discussions with family rather than professionals.
Life-Cycle of Engineering Systems, 2016
International Electron Devices Meeting 1998. Technical Digest (Cat. No.98CH36217)
There is a need for low cost, efficient field emission materials for use in flat panel displays. ... more There is a need for low cost, efficient field emission materials for use in flat panel displays. The discovery, by the authors, of high emission currents from `spin-on' materials, consisting of conjugated polymers, is, therefore, of potential importance. Analysis based on the presence of space charge limited currents in the polymer films is described and comparison is made with measurement
Life-Cycle of Civil Engineering Systems, 2014
Stress concentration factor (SCF) analysis is carried out for welded T-joints made up of steel ci... more Stress concentration factor (SCF) analysis is carried out for welded T-joints made up of steel circular hollow section brace welded onto concrete-filled circular hollow section chord. A finite element model has been developed employing ABAQUS software to simulate the performance of T-joints with concrete-filled chords under axial force on the brace. Modelling of the weld profile has been included in the simulation. An 8-node 3D hexahedral solid element with full integration scheme has been employed in the simulation. The interaction between the chord and concrete filling has been assumed to be due to friction only. The hot spot stresses have been obtained by linear extrapolation of the stresses in the region recommended by CIDECT. The outcome of the numerical simulation is verified using existing experimental results obtained by Wang et al. (2013)
MRS Proceedings, 1999
ABSTRACTCarbon based materials are considered to be amongst the most promising field emitters for... more ABSTRACTCarbon based materials are considered to be amongst the most promising field emitters for use in displays. Semiconducting polymer (regioregular poly3 octylthiophene) has been found by the authors to have the lowest threshold field reported to date for any carbon based material. The emission process is, we believe, associated with surface irregularities, voids, possibly resulting from solvent evaporation. Field intensification occurs, and as a consequence there is field emission from the top ridges of the voids. The current flowing through these regions is controlled by space charge in traps in the upper half of the energy gap. There is, in addition, current injected from the base of the voids and the two currents mix to give field emission with current IαV1.8 where V is the anode voltage. Measurements on capacitor samples using Aluminium, Gold and Calcium electrodes have been used to examine the conduction processes in the material and these are linked to results of field em...
Environment and Pollution, 2014
Thin Solid Films, 2011
Polyfluorene (PF) and its derivatives are very promising candidates for organic light emitting di... more Polyfluorene (PF) and its derivatives are very promising candidates for organic light emitting diodes (OLEDs) in lighting applications because of their high photoluminescence and electroluminescence efficiencies. Recent investigations of potential materials for OLEDs have shown that introducing n-type inorganic nanoparticles into conjugated polymers is efficient to produce stable and high performance devices. In this study, composite thin films made by incorporation of zinc oxide (ZnO) nanoparticles into a PF derivative have been prepared and their optical properties have been investigated. The prepared thin films were stored in different media (in air, in vacuum, in the dark or exposed to light) in order to study environmental influences on the material stability. Analysis of spectral data obtained from infrared (IR), Raman, UV-vis, and photoluminescence (PL) measurements shows a large enhancement in luminescence for polymer nanocomposites while using high nanoparticle concentrations (within a limit of 10% ZnO). Time-resolved PL performed on those nanocomposite films corroborated the above result: it indicated that the light-emission enhancement can be explained by efficient energy transfer from nanoparticles to the polymer chains and increase of the chain separation distance. In addition, the nanocomposites were found to be more stable than pristine polymer films whatever the storage conditions were used. It was confirmed by IR analysis that incorporation of nanoparticles into polymers prohibited the formation of fluorenonyl groups in PF chains, which was identified as the main cause of the degradation of the polymer under photo-oxidation.
Synthetic Metals, 1998
Abstract The methods of reflection and transmission are used to determine the optical constants n... more Abstract The methods of reflection and transmission are used to determine the optical constants n and k of thin films of regioregular poly (3-octylthiophene). The technique is based on the simultaneous use of Fresnel laws and the dispersion relations between n and k of the film using an iterative process. The optical and Tauc gaps are also derived.
Journal of Applied Physics, 1997
We present an observation of extensive space-charge limited conduction in polybenzo[c]thiophene. ... more We present an observation of extensive space-charge limited conduction in polybenzo[c]thiophene. Strong evidence for the presence of three discrete trapping levels is shown with a possibility of a fourth trap level. The density of traps for the first three levels is found to be 5×1016 cm−3, 1×1017 cm−3, and 2×1017 cm−3, respectively. A lower limit for the free-carrier mobility was estimated to be ∼3×10−5 cm2 V−1 s−1.
Journal of Applied Physics, 1998
The temperature dependence of space-charge-limited currents in polybenzo[c]thiophene (PBCT) films... more The temperature dependence of space-charge-limited currents in polybenzo[c]thiophene (PBCT) films in a sandwich structure of aluminum/PBCT/indium–tin–oxide is presented. Free carrier space-charge-limited currents are identified and the free carrier mobility has been estimated to be ∼3×10−5 cm2 V−1 s−1. A trap of concentration ∼1.8×1017 cm−3 and energy ∼0.67 eV from the highest occupied molecular orbital level is estimated. The thickness dependence of the current, at constant voltage, is very close to that expected for a space-charge-limited mechanism. The Tauc band gap determined by optical spectrophotometry was found to be ∼1.34 eV.
Japanese Journal of Applied Physics, 1998
An investigation into the effect of carrier trapping in polymer Schottky diodes is presented. The... more An investigation into the effect of carrier trapping in polymer Schottky diodes is presented. The diodes have been fabricated using regioregular poly(3-octylthiophene) as the semiconductor and aluminium and indium doped tin-oxide as the rectifying and ohmic contacts respectively. The diodes show rectification ratios up to 3–4 orders of magnitude. Evidence for image-force lowering of the Schottky barrier is observed. The frequency dependence of the capacitance, conductance and dielectric loss is analysed, from which detailed information on the metal/semiconductor interface and the doping level is obtained. An equivalent circuit is proposed.