Heterojunction

CdS has been proved to be an ideal material for use as the window layer for heterojunction solar cells especially with n-CdS/p-CdTe. CdS, Cd0. 9Sn0. 1S and Cd0. 8Sn0. 2S films were deposited onto glass substrates at 300° C substrate temperature by using ultrasonic spray ...

Herein, MoS2-ZnO heterostructure nanorods were hydrothermally synthesized and characterized in detail using several compositional, optical, and morphological techniques. The comprehensive characterizations show that the synthesized MoS2/ZnO heterostructure nanorods were composed of wurtzite hexagonal phase of ZnO and rhombohedral phase of MoS2. The synthesized MoS2/ZnO heterostructure nanorods were used as a potent photocatalyst for the decomposition of methylene blue (MB) dye under natural sunlight. The prepared MoS2/ZnO heterostructure nanorods exhibited ~97% removal of MB in the reaction time of 20 min with the catalyst amount of 0.15 g/L. The kinetic study revealed that the photocatalytic removal of MB was found to be in accordance with pseudo first-order reaction kinetics with an obtained rate constant of 0.16262 min−1. The tremendous photocatalytic performance of MoS2-ZnO heterostructure nanorods could be accredited to an effective charge transportation and inhibition in the r...

This study describes the preparation of graphitic carbon nitride (g-C3N4), hematite (α-Fe2O3), and their g-C3N4/α-Fe2O3 heterostructure for the photocatalytic removal of methyl orange (MO) under visible light illumination. The facile hydrothermal approach was utilized for the preparation of the nanomaterials. Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET) were carried out to study the physiochemical and optoelectronic properties of all the synthesized photocatalysts. Based on the X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance (DRS) results, an energy level diagram vs. SHE was established. The acquired results indicated that the nanocomposite exhibited a type-II heterojunction and degraded the MO dye by 97%. The degradation ability of the nanocomposite was higher than that of pristine g-C3N4 (41%) and α-Fe2O3 (30%) photocatalysts under 300 min of light irradiation. The form...

We have studied the thermodynamic density of states (or compressibility) of a two-dimensional hole gas in a p-GaAs/AlGaAs heterostructure in the presence of a titled magnetic field. When a magnetic field parallel to the 2D surface is applied, the system exhibits a giant positive magnetoresistance [1]. However, the width of the Landau levels does not depend on the parallel component

We have studied the thermodynamic density of states (or compressibility) of a two-dimensional hole gas in a p-GaAs/AlGaAs heterostructure in the presence of a titled magnetic field. When a magnetic field parallel to the 2D surface is applied, the system exhibits a giant positive magnetoresistance [1]. However, the width of the Landau levels does not depend on the parallel component

GaInP-GaAs heterojunction bipolar phototransistors grown by metal organic vapor phase epitaxy (MOVPE) and operated with frontside optical injection through the emitter are reported with high optical gain (< 88) and record high frequency performance (28 GHz). ...

1-μm-thick GaN layers were obtained in one growth procedure on compliant SiC/Si(111) substrates using plasma-assisted molecular beam epitaxy (PA MBE). Si(111) substrates were modified by the atoms substitution technique. Prior to the atoms substitution procedure, on the one substrate, the transition porous Si layer (por-Si) was performed. The GaN layer grown on this substrate revealed better surface morphology and structural quality, less threading dislocation density, and as a result, showed lower free carrier concentration and higher carrier mobility. Moreover, the XRD study revealed less strain level in the GaN layer grown on the por-Si layer.

This work describes infrared (IR) photon detector techniques based on novel semiconductor device concepts and detector designs. The aim of the investigation was to examine alternative IR detection concepts with a view to resolve some of the issues of existing IR detectors such as operating temperature and response range. Systems were fabricated to demonstrate the following IR detection concepts and determine detector parameters: (i) Near-infrared (NIR) detection based on dye-sensitization of nanostructured semiconductors, (ii) Displacement currents in semiconductor quantum dots (QDs) embedded dielectric media, (iii) Split-off band transitions in GaAs/AlGaAs heterojunction interfacial workfunction internal photoemission (HEIWIP) detectors. A far-infrared detector based on GaSb homojunction interfacial workfunction internal photoemission (HIWIP) structure is also discussed. Device concepts, detector structures, and experimental results discussed in the text are summarized below. Dye-s...

Solar cell technology based on carrier-selective contact layers has been envisaged as a prominent photovoltaic (PV) design for enhancing the efficiency of silicon heterostructure devices. Because of its higher work function, the carrier-selective layer such as Molybdenum oxide (MoOx) assists in pinning the Fermi level at the interface between crystalline silicon (c-Si) and MoOx. This enables easier extraction of charge carriers from the interface for electrical conduction, thus improving the device performance. In this paper, MoOx has been employed as a back surface field layer (BSF) of p-n junction solar cell for efficient separation of photogenerated charge carriers. The correlation of various parameters, such as MoOx work function, its thickness, and c-Si wafer doping concentration to the PV performance of the device has been demonstrated by employing Silvaco TCAD simulation. Comparative analysis has also been drawn to the reference structure based on p-a-Si:H BSF film. The simulated results exhibited an efficiency of 14.7% for MoOx-based device as compared to 13.6% for the reference solar cell. The obtained efficiency of MoOx-based devices can be boosted to ~19% by the inclusion of surface passivation layers.

A paradigm for high-quality factor (Q) with a substantial fulfillment for appraising sensing ability and performance has been investigated. Through constructing a 1D (one-dimensional) topological photonic crystal (PhC) mirror heterostructure, which is formed by the image view of 1D topological PhC stacking with its original one. In the 1D topological PhC-mirror heterostructure, there is an interesting mode that appeared with the symmetric, typical Lorentzian-line shape with 100% transmittance in the topological mirror edge-state mode (hybrid resonance mode) at the heterostructure interface. Physically, such a mode is a defect mode, but the defect is introduced through topological operations. The high Q-factor of 5.08 × 104 is obtained due to the strong optical localization of the defect mode at the topological edge area. Consequently, this device acts as a narrow passband filter. Moreover, due to the narrow bandpass property, it may be an advantageous reference for many applications...

In this paper, a p–n thin film NiO/ZnO heterojunction for a rectifier diode and a UV photodetector is prepared and characterized. Nickel oxide (NiO) and gallium-doped zinc oxide (ZnO:Ga) thin films are grown by RF magnetron sputtering and spray pyrolysis techniques, respectively. The crystal structure of the thin films is studied by the X-ray diffraction (XRD) method. The transmittance and reflectance are studied by UV–VIS spectroscopy. The p–n electrical parameters are estimated from current–voltage characteristics. The effects of duration of thermal annealing at 450oC on the characteristics of the NiO/ZnO:Ga device are evaluated. The non-annealed diode shows the best rectification coefficient of 105 at ±1 V. The p–n photodetection capability is studied under UV illumination. At a reverse bias of –3 V under 365-nm UV illumination, the device shows a current intensity of ~6.2 × 10-12 A. The observed increase in the reverse current intensity by about two orders of magnitude under a U...

Laser-induced deposition was employed to grow HgCdTe thin films on Si substrate at a temperature of ≲190°C. Auger spectroscopy and optical and electrical measurements demonstrate that the quality of films obtained is strongly dependent on the type of source and quality of the Si substrates.

Arylenevinylene-co-pyrrolenevinylene (AVPV) is a promising candidate amongst the group of new photovoltaic materials. It is a low band gap organic material with a band gap of 1.84 eV and absorbs sunlight in 300–700 nm range. In this paper, we demonstrate the ...

Transition metal oxides (TMOs) have gained interest in photovoltaic community for their usages as dopant-free carrier-selective contacts in silicon based solar cells. TMOs such as MoOx, WOx, V2Ox, NiOx with high work function are used as hole-selective contacts whereas TiO2, ZnO are used as electron-selective contacts. We have fabricated solar cells using molybdenum trioxide (MoO3-x, x  88% in visible region and have band gap of 3.43 eV. As molybdenum trioxide has high work function ∼6.6 eV, it helps in the transport of holes in this structure. We have achieved power conversion efficiency of 4.44%, current density 28.44 mA/cm2 and open-circuit voltage 391 mV. Further optimization of processing parameter is necessary to improve the performance of these solar cells.

It is shown for the first time that the structural and optical functional characteristics of integrated GaAs/Si(100) heterostructures can be controlled by using misoriented Si(100) substrates and their preliminary etching. The growth of an epitaxial GaAs layer on a Si substrate without the formation of antiphase domains can be carried out on a substrate deviated from the (100) singular plane by an angle smaller than 4°–6° or without a transition layer of GaAs nanocolumns. Preliminary treatment of the silicon substrate by etching makes it possible to use it for the vapor-phase epitaxial growth of a single-crystal GaAs film with a considerably smaller relaxation coefficient, which has a positive effect on the structural quality of the film. These data are in good agreement with the results of IR reflectance spectroscopy and photoluminescence and ultraviolet spectroscopy. The features of the optical properties of integrated GaAs/Si(100) heterostructures in the infrared and ultraviolet spectral regions are also defined by the relaxation coefficient.

Conductive-probe atomic force microscopy (CP-AFM) measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features