Effect of Microindentation on Electroluminescence of SiC P-I-N Junctions

The influence of microindentation on the electroluminescence of silicon carbide was studied in forward-biased 4H SiC p-i-n junctions. Four spectral regions at approximately 390, 420, 445 and 500 nm initially observed on virgin samples strongly depend, in regard to magnitude, on the condition of the starting die. These spectral regions may be interpreted as arising from either phonon-assisted band-to-band transitions or from defect-related transitions. The same SiC die were then subjected to mechanical damage brought about by a series of closely spaced microindentations directed approximately perpendicular to the c-axis. The spectra taken after a first set and subsequently a second set of microindentations are distinct from the initial spectra in all cases, and differences are interpreted as being due to the modification of existing defects or additional defects being generated mechanically. The influence of microindentation on the ideality factor is measured and discussed. Measured light flux with respect to a standard light source is also shown at each microindentation stage.

Photodetector based on Rutile and Anatase TiO2 nanostructures/n-Si Heterojunction

Rutile and anatase titanium dioxide TiO2 nanostructures has been prepared successfully by hydrothermal technique. Also Rutile and anatase TiO2/n-Si heterojunction detector (HJ) has been fabricated. Hall Effect measurements confirmed that prepared films are n-type. The optical absorption spectra showed the prepared films have peak absorption in UV region. TiO2/n-Si heterojunction had exhibited diode-like rectifying I-V behaviour in the dark as well as under the illumination. Ideality factor greater than 2 and rectification factor for Rutile TiO2/n-Si HJ is equal 32.0961 higher than anatase TiO2/n-Si HJ. Photodetetor based on rutile TiO2/n-Si HJ showed higher responsivity and incident photon-to-current efficiency (IPCE) than photodetector based on anatase TiO2/n-Si HJ. Photodetetor based on rutile TiO2/n-Si HJ has responsivity is 69.11Amp/W at 570 nm and IPCE is 21.2%at 370nm and 1.38% at 570nm. For the purpose of investigating the impacts of TiO2 crystal phase upon the performance of the device despite the fact that rutile has a lower band gap compared to anatase, rutile exhibits better photovoltaic activity due to its higher specific surface area.

Negative series resistance and photo-response properties of Au/PPY-MWCNTs composite /TiO2/Al2O3/n-Si/Al photodiode

The paper addresses a novel approach concerning the appearance of negative series resistance (Rs) at high frequencies for both temperatures and voltages. Most of the previous studies have focused on the relationship between voltage and current (I - V) to determine the value of Rs using several methods. By measuring capacitance and conductance as a function of voltage, we were able to develop a systematic analysis of series resistance. At high frequencies of 2×107, 107 Hz, Rs has negative values however, at frequency 106Hz it takes both positive and negative values, whilst from (105 - 10) Hz it has positive values. Here in this article, we synthesized Au/PPY-MWCNTs/TiO2/Al2O3/n-Si/Al structure which can be used in a variety of applications such as supercapacitors, and diodes. We investigated the electrical properties such as ideality factor (n), barrier height (фb), series resistance using several approaches such as conventional, Chueng, and Nord methods. The structure has shown rectification with a good response to daylight illumination. The structure response to daylight illumination indicates that photodiodes have the potential to be used as solar detectors.

Characterization of Electrical Parameters of Copper Phthalocyanine Based Organic Electronic Device in Presence of Fullerene Nanoparticles

Characterization of electrical parameters of Copper Phthalocyanine dye has been done in the present work. In the context of electrical parameters, the Schottky barrier and ideality factor of the organic device has been measured and the effects of fullerene nanoparticles on these parameters have been studied. Analysis of electrical parameters has been done by the current-voltage characteristics of the device. The influence of fullerene nanoparticles lessens the Schottky barrier to 0.71 eV from 0.75 eV. The current flow is assumed to be injection limited as the Schottky barrier is greater than 0.3 eV - 0.4 eV. The Schottky barrier is also estimated by the Norde method. Norde's method shows lessening of barrier height from 0.70 eV to 0.65 eV under the influence of fullerene nanoparticles. The measured ideality factor value reduces from 3.787 to 1.495 in presence of fullerene nanoparticles. The charge injection mechanism at metal-organic contact gets influenced by the interfacial Schottky barrier height. Decrease in both Schottky barrier and ideality factor attribute to the increase in charge flow and it allows a reduction in the device’s transition voltage from 2.5 V to 1.0 V.

A method of determining the parameters in systems with serialized Current-Voltage characteristics

We propose a method of determining the parameters of systems with serialized characteristics, which may suggest the existence of symmetry in the system. The method is demonstrated in extracting the parameters of a metal-semiconductor in the presence of significant series resistance, which is itself important but limits the accuracy of the existing methods in the determination of the other calculated parameters such as barrier height and ideality factor. We show the steps involved in establishing whether symmetry exists, and show that some functional interrelations between the parameters and the independent variables can readily be established. We use actual measurement data from an experimental diode and show that the results outperform the popular Cheung-Cheung approach. This general approach, therefore, represents a significant advancement in the analysis of serialized empirical data.

Dirac-Source Diode with Sub-unity Ideality Factor

An increase in power consumption necessitates a low-power circuit technology to extend Moore’s law. Low-power transistors, such as tunnel field-effect transistors (TFETs)1-5, negative-capacitance field-effect transistors (NC-FETs)6, and Dirac-source field-effect transistors (DS-FETs)7-10, have been realised to break the thermionic limit of the subthreshold swing (SS). However, a low-power diode rectifier, which breaks the thermionic limit of an ideality factor (η) of 1 at room temperature, has not been proposed yet. In this study, we have realised a DS diode, which exhibits a steep-slope characteristic curve, by utilising the linear density of states (DOSs) of graphene7. For the developed DS diode, η < 1 for more than two decades of drain current with a minimum value of 0.8, and the rectifying ratio is large (> 105). The realisation of a DS diode paves the way for the development of low-power electronic circuits.

Impact of Substrate Temperature on Structural, electric and Optical characteristics of CuO Thin Films grown by JNS Pyrolysis Technique

JNS pyrolysis route has been successfully employed to grow CuO thin films at various substrate temperature, ranging from 300 to 600˚C. The XRD analyses revealed the monoclinic phased polycrystalline growth of the samples and exhibited the strong influence of the substrate temperature (ST) on the crystallite sizes. Optical transmission and bandgap studies also showed that sample bandgaps clearly rely upon the growth temperatures. The SEM micrographs displayed the agglomerated growth of particles having golf ball-like structures. The occurrence of Cu and O in the samples were confirmed through EDS analyses. The studies on DC electrical conductivities also shows strong dependency on the ST. A p-CuO/n-Si diode was fabricated at the ST of 600˚C and the diode parameters like barrier height ( ϕb ) and ideality factor (n) were determined under light and dark conditions.