No abstract

No abstract

The study aimed at the investigation and application of SnS thin film semiconductor as a channel layer semiconductor in the assembly of an electric double layer field effect transistor which is important for the achievement and development of novel device concepts, applications and tuning of physical properties of materials since the reported EDLFET and the modulation of electronic states have so far been realised on oxides, nitrides, carbon nanotubes and organic semiconductor but has been rarely reported for the chalcogenides. Honey was used as a gel like electrolytic gate dielectric to generate an enhanced electric field response over SnS semiconductor channel layer and due to its ability to produces high on-current and low voltage operation while forming an ionic gel-like solution similar to ionic gels which consist of ionic liguids. SnS gated honey Electric double layer field effect transistor was assembled using tin sulphide (SnS) thin film as semiconductor channel layer and honey as gate dielectric. The measured gate capacitance of honey using LCR meter was measured as 2.15 μF/ cm2 while the dielectric constant is 20.50. The semiconductor layer was deposited using Aerosol assisted chemical vapour deposition and annealed in open air at 250 on an etched region about the middle of a 4×4 mm FTO glass substrate with the source and drain electrode region defined by the etching and masking at the two ends of the substrate. Iridium was used as the gate electrode while a copper wire was masked to the source and drain region to create electrode contact. The Profilometry, X-ray diffraction, Scanning electron microscope, Energy dispersive X-ray spectroscopy, Hall Effect measurement and digital multimeters were used to characterise the device. The SnS thin film was found to be polycrystalline consisting of Sn and S elements with define grains, an optical band of 1.42 eV and of 0.4 μm thickness. The transistor operated with a p type channel conductivity in a depletion mode with a field effect mobility of 16.67 cm2/Vs, cut-off voltage of 1.6 V, Drain saturation current of1.35μA, a transconductance of -809.61 nA/V and a sub threshold slope of -1.6 Vdec-1 which is comparable to standard specifications in Electronics Data sheets. Positive gate bias results in a shift in the cut off voltage due to charge trapping in the channel/dielectric interface.

No abstract

The study aimed at enhancement and optimisation of SnS conductivity via annealing for field effect transistor’s semiconductor channel layer application. Interstitials and vacancies in SnS films are known to cause carrier traps which limit charge carriers and hence limit the achievement of the threshold voltage for a field effect transistor operation. Tuning of SnS conductivity for transistor application is of emerging interest for novel device operation. SnS thin film semiconductors of 0.4 thickness were deposited using Aerosol assisted chemical vapour deposition and annealed in open air at annealing temperatures of150, 200, 250, 300 and 350 . Variation of the annealing temperature from 150 through 250 enhances the crystallinity of the annealed thin film samples by increasing the number of crystallites of the annealed films which is also buttress by the decreasing values of FWHM. However a further decrease in crystallite size at higher annealing temperature of 300 to 350 was observed which could be attributed to the fragmentation of clusters of crystallites at higher annealing temperature. Increase in annealing temperature increases grain size leading to the reduction in grain boundaries and potential barrier thereby changing the structure and phase of the films which in essence affects the electrical conductivity of the SnS thin films. The films annealed at 250 exhibited optimum conductivity. The average hall coefficients of the samples deposited at 150 to 250 were positive which indicates that the films annealed at this temperature range are of p type conduction while the average hall coefficients of the samples deposited at 300 and 350 were negative indicating that the films are of n type conduction. The conductivity change is essential for the use of SnS as a semiconductor channel layer especially in a field effect transistor where the device can be tuned to work as a p type or n type semiconductor channel layer.