This work reports on structural, electrical, optical, and photosensing properties of La and Zn co-doped CdO thin films. The co-doped CdO thin films were prepared on glass substrates using the nebulizer spray method at 350 C. From the structural analysis, a decrease in the crystallite size from 20 to 16 nm is observed against the incorporation of La in CdO:Zn. Inclusion of La in CdO:Zn has also changed the surface morphology with a reduction in the roughness of the thin film samples. EDX analysis confirmed the incorporation of La with CdO: Zn in the prepared films. The bandgap value of the prepared samples increased with the increase in La concentration. A 1.5 wt % of La co-doped with CdO:Zn thin film sample produces low resistivity of 6.81 x 10(-4) omega cm and a better figure of merit of 8.4 x 10(-4) omega(-1). Finally, the fabricated photodetector with 1.5 wt% of La co-doped with CdO:Zn thin film shows a higher photocurrent and an ideality factor value of 3.4. The photosensing properties of the fabricated (p-Si/CdO-Zn-La (1.5%)) photodetector shows a higher responsivity (R) value of 1.18 AW(-1), specific detectivity (D*) value of 4.90 x 10(9) Jones, and external quantum efficiency (EQE) value of 274% with 3.0 mW/cm(2) light intensity. The switching characteristics of the photodetector show a faster rise time (2.9s) and fall time (3.6s) suggesting the fabricated device suitable for photosensing applications.
The transmission and transport properties of non-conventional Fermi velocity graphene superlattices (FVGSLs) are studied. Arithmetic, regular and random distributions of the Fermi velocity barriers are assessed. A velocity position-dependent Dirac-like Hamiltonian is used to describe the charge carriers. The transfer matrix method and the Landauer-Büttiker formalism are implemented to obtain the transmission and the integrated transmission (conductance) at zero temperature. We find that arithmetic FVGSLs show peculiar transport characteristics as compared to regular and random FVGSLs. In particular, the arithmetic profile eliminates the regular and irregular oscillations of the integrated transmission typical of regular and random FVGSLs. More importantly, arithmetic FVGSLs keep the integrated transmission around the same value regardless of the size of the system, presenting even an increase (crossover) with the size of the system for large Fermi velocity ratios. This contrasts with the systematic reduction of the integrated transmission with the size of the system for regular and random FVGSLs. We delve into the possible causes of the crossover of the integrated transmission for arithmetic FVGSLs.
Molybdenum trioxide (MoO3) thin films with thicknesses 300, 400 and 500 nm were deposited on an FTO substrate by thermal evaporation method. The prepared thin films showed both thermochromic and photocatalytic dye degradation properties. The thermochromic property of the prepared thin films was induced by exposing the thin films to argon gas at a temperature varying from 100 degrees C to 300 degrees C (in steps of 50 degrees C). The photocatalytic dye degradation ability of the films were examined by the photodegradation of methylene blue (MB) dye solution under visible light irradiation. MoO3 thin film with 300 nm thickness is seen to have good thermochromic and photocatalytic dye degradation ability and both of these properties are necessary for smart window applications.
In this theoretical investigation, the binding energy, the binding energy Stark-shift, the dipole moment, the polarizability, and the diamagnetic susceptibility related with a confined shallow donor impurity in zinc blende GaN conical-shaped quantum dots are calculated under the effect of an electric field applied along the z-direction. Calculations have been made by using a variational approach within the infinite confining potential model and considering the parabolic conduction band and the effective mass approximations. The results suggest important dependencies of the calculated physical properties on the variation of the dot dimensions, axial impurity position, and the intensity of the applied electric field. It is observed that: i) the binding energy Stark shift increases up to a maximum value and then decreases with increasing the strength of the electric field, and it is strongly influenced by the impurity position and geometrical parameters, ii) for a fixed electric field value, the binding energy Stark shift is always an increasing function of the dot height, and iii) for fixed electric field values, the binding energy Stark shift shows a mixed behavior concerning the dot radius, i.e., for low field strength, the binding energy is always a growing function of the radius, and for large field strengths, such physical quantity grows with the radius up to a maximum and then decreases. Furthermore, the electric field (the strong quantum confinement) enhances slightly (diminishes) the diamagnetic susceptibility of impurity.
The work deals with the implementation of charge plasma concept towards the formation of graded doping profile in the Drain region of Tunnel FET (TFET) device architecture. This new and innovative concept of graded doping profile in the lateral direction holds its merit towards stopping the ambipolar conduction in TFETs without affecting its off and the on state performance. The proposed device i.e. Undoped Drain Graded Doping based TFET (UDGD TFET) architecture is highly effective in suppressing the gate to drain and therefore the total gate capacitance values and thus also seems promising towards reduction in the dynamic power dissipation in TFETs. The architecture has also shown significant improvements for RF application in terms of cut-off frequency, Gain Bandwidth and Transit Time with optimized parameters such as gate work function, drain workfunction, channel length and drain region length when compared to conventional Tunnel FETs.
