Photodetector Applications Research Articles

(Invited) Ultrathin Gap Nanoantenna: Crystal Phase Transitions and Luminescent Properties

We report Te-doped GaP nanowires (NWs) with positive tapering and radii measuring as low as 5 nm grown by the self-assisted vapor-liquid-solid mechanism using selective-area molecular beam epitaxy. The occurrence of the ultrathin nanoantenna showed a dependence on pattern pitch (separation between NWs) with a predominance at 600 nm pitch, and exhibited radius oscillations that correlate with polytypic zincblende/wurtzite segments. A growth model explains the positive tapering of the NW leading to an ultrathin tip from the suppression of surface diffusion of Ga adatoms on the NW sidewalls by Te dopant flux. The model also provides a relationship between the radius modulations and the oscillations of the droplet contact angle, predicting the quasi-periodic radius oscillations and corresponding crystal phase transitions. The GaP NWs showed strong low temperature micro-photoluminescence exciton-related emission, indicating a bandgap difference between the zincblende/wurtzite segments, with phonon replicas due to the transverse optical phonon mode. These results establish a link between dopants and the ability to control NW morphology, crystal phase and luminescent properties with possible applications in thermoelectrics, quantum emitters and photodetectors.

Low Frequency Electronic Noise Characterization of Au-W/β-Ga2O3 Schottky Diodes

Ultra-wide bandgap (UWBG) semiconductors have attracted tremendous amount of interest for applications in high-power electronics and solar-blind UV photodetectors. In particular, β-Ga2O3 has attracted significant research attention in recent years due to its promising electrical and optical characteristics including a large bandgap, high breakdown electrical field, and large Baliga’s figure of merit compared to well-established wide-bandgap technologies such as GaN and SiC [1].Low frequency electronic noise, which is present in all electronic devices, can be used as a diagnostic tool for semiconductor material and device characterization. By studying the low frequency noise in semiconductor materials and devices, the physics associated with the noise properties of bulk and interface defects and traps can be investigated [2]. Measurement of low frequency noise is also crucial for evaluating material quality and device reliability.In this work, we investigate the forward-bias diode parameters and low-frequency electronic noise in Au-W/β-Ga2O3 Schottky barrier diodes. The Schottky contact is formed by depositing 20 nm of Tungsten (W) using dc sputtering followed by 340 nm of Gold (Au) using e-beam evaporation, and subsequent annealing [3].We first measure the I-V characteristics and extract important diode parameters, such as the Schottky barrier height, ideality factor, and series resistance from room temperature forward-bias current-voltage characteristics. The extracted Schottky barrier height for these devices is in the range 0.7-0.8 eV and the ideality factor is approximately 1.2.We next measure the low-frequency electronic noise in Au-W/β-Ga2O3 Schottky diodes at different forward bias voltages at room temperature. We find that the current noise spectral density exhibits 1/f-type behavior for all forward bias voltages at low frequency with an exponent ranging from 0.75 to 1.15, indicating that the low frequency noise of these devices is dominated by excess (flicker) noise. No Lorentzian-shaped generation-recombination (G-R) noise is observed. At low frequencies, the shot noise contribution is found to be negligible for the values of the current in our devices, and the total noise is 1/f-limited.We also investigate the dependence of the current noise spectral density on forward bias current, revealing different relationships in different current regimes. At low currents, the noise spectral density is found to scale approximately as the square of current, whereas at high currents, the noise spectral density begins to saturate. Such noise behavior can be attributed to different noise sources dominating in different current regimes. Furthermore, using the noise figure of merit adapted for ultra-wide bandgap semiconductor devices [4], we find that the Au-W/β-Ga2O3 devices have lower noise levels compared to other emerging UWBG materials and similar noise levels as well-established technologies such as GaN.These results provide important insights into the electronic noise properties of Au-W/β-Ga2O3 Schottky diodes and show that low frequency noise characterization is an important diagnostic tool for assessing the quality and reliability of gallium oxide based wide-bandgap materials and device technologies.

Polymer-Gel-Derived PbS/C Composite Nanosheets and Their Photoelectronic Response Properties Studies in the NIR

Non-conjugated polymer-derived functional nanocomposites are one of the important ways to develop multifunctional hybrids. By increasing the degree of crosslinking, their photophysical properties can be improved. PbS is a class of narrow bandgap infrared active materials. To avoid aggregation and passivation of the surface defects of PbS nanomaterials, a large number of organic and inorganic ligands are usually used. In this study, PbS/C composite nanosheets were synthesized with Pb2+ ion-crosslinked sodium alginate gel by one-pot carbonization. The resulting nanosheets were coated on untreated A4 printing paper, and the electrodes were the graphite electrodes with 5B pencil drawings. The photocurrent signals of the products were measured using typical 650, 808, 980, and 1064 nm light sources. The results showed that the photocurrent switching signals were effectively extracted in the visible and near-infrared regions, which was attributed to the mutual passivation of defects during the in situ preparation of PbS and carbon nanomaterials. At the same time, the resulting nanocomposite exhibited electrical switching responses to the applied strain to a certain extent. The photophysical and defect passivation mechanisms were discussed based on the aggregation state of the carbon hybrid and the interfacial electron interaction. This material would have potential applications in broadband flexible photodetectors, tentacle sensors, or light harvesting interdisciplinary areas. This study provided a facile approach to prepare a low-cost hybrid with external stimulus response and multifunctionality. These results show that the interfacial charge transfer is the direct experimental evidence of interfacial interaction, and the regulation of interfacial interaction can improve the physical and chemical properties of nanocomposites, which can meet the interdisciplinary application. The interdisciplinary and application of more non-conjugated polymer systems in some frontier areas will be expanded upon.

Lattice Manipulation with Di-Tertiary Ammonium Spacer in Bismuth Bromide Perovskite Directs Efficient Charge Transport and Suppressed Ion Migration for Photodetector Applications.

Bismuth halide hybrid perovskites have emerged as promising alternatives to their lead halide homologs because of high chemical stability, low toxicity, and structural diversity. However, their advancements in optoelectronic field are plagued with poor charge transport, due to considerable microstrain triggered by bulky spacer. Herein, the di-tertiary ammonium spacer (N,N,N',N'-tetramethyl-1,4-butanediammonium, TMBD) is explored to direct stable 1D bismuth bromide lattice structure with relaxed microstrain. Compared to the primary pentamethylenediamine (PD)2+, the (TMBD)2+ adopting alternating alignment enables a unique H-bonds mode to distort the configuration of inorganic layers to form corner-sharing [BiBr5] near-regular chains with narrower bandgap, lower exciton binding energy, and reduced carrier-lattice interactions, thereby facilitating charge-carrier transport. Moreover, the (TMBD)2+ spacers largely suppress ion migration in perovskite lattice, as substantiated by the experimental and theoretical investigations. Consequently, (TMBD)BiBr5 single crystal photodetector delivers a 185-fold increase in current on/off ratio with respect to (PD)BiBr5 under white light irradiation, considerable responsivity (≈82.97mA W-1), detectivity (≈8.06 ×1011 Jones) under weak light (0.02mW cm-2) irradiation, in the top rank of the reported hybrid bismuth halide perovskites. This finding offers novel design criterion for high-performance lead-free perovskites.

Tunable Band Alignment and Optoelectronic Structure of Cu2Se/PtX2 (X=Se,Te) Heterostructures: under Strain and Electric Field

Two-dimensional (2D) material-based van der Waals heterostructures (vdWHs) are an emerging strategy for regulating the electronic properties of two-dimensional materials. This study investigated the effects of a vertical electric field and strain on the band alignment transition and optoelectronic properties of Cu2Se/PtSe2 (PtTe2) vdWHs using density functional theory calculations. Cu2Se/PtSe2 vdWHs exhibited type-I to type-II band alignment transformation under an in-plane strain, interlayer distance, and electric field of 2%, 2.40 Å, and -0.40 V/Å, respectively. Moreover, Cu2Se/PtTe2 vdWH demonstrated a rich transition of types I, II, and III band alignments with in-plane strain. The absorption spectra of Cu2Se/PtSe2 (PtTe2) vdWHs show a certain degree of blue and red shift phenomenon upon the application of strain and electric fields. The predicted power conversion efficiencies at 3% in-plane strain with an interlayer distance of 3.40 Å for Cu2Se/PtSe2 (PtTe2) vdWHs were observed to be as high as 22.58% (19.80%). Thus, our work demonstrated that both strain and electric field can effectively and flexibly control the electronic properties of Cu2Se/PtSe2 (PtTe2) vdWHs, making them a promising candidate material for applications in photodetectors and field-effect transistors.

Comprehensive investigation on ruthenium doped Sn2S3 thin films for photo sensing applications

This study investigates the deposition of tin trisulfide (Sn2S3) films onto glass substrates through the nebulizer spray technique, employing aqueous solutions of SnCl2 and SC (NH2)2 at a molar ratio of Sn to S of 1:2 under various doping concentrations of ruthenium (1, 2, 3, 4, and 5 wt %). The crystallography, morphology, chemical, optical and photo sensing characteristics of deposited thin films has been comprehensively analysed using an X-ray diffractometer, Field emission scanning electron microscope annexed with energy dispersive X-ray analyser, UV-VIS spectrometer, Photoluminescence spectroscopy and a digital Keithley source meter. The X-ray diffraction investigation clearly establishes the polycrystalline nature of the films possessing orthorhombic crystal structure. The surface morphology was visualized via Field Emission Scanning Electron Microscope which confirmed the existence of spherical nano grains at 3 % Ru doping concentration. The energy dispersive X-ray analyser spectrum was used to probe the elements present in the prepared thin film and it supports the presence of Sn, S and Ru. The optical absorption and transmittance spectra were observed in the wavelength range between 450 and 900 nm for all the samples. Enhanced absorption in the visible region is observed from the absorption spectra. Direct allowed band gap values ranging around 2.05 eV–1.92 eV is observed for these Ru doped spray pyrolyzed Sn2S3 thin films. The I–V characteristics of the samples, studied under both light and dark conditions, demonstrate an increase in current values with higher concentrations of Ru doping. The highest value of the photo current (36 μA) was observed for 3 wt % ruthenium doped film. Highest responsivity of 67.6 × 10−2 A/W was observed for 3 % Ru doped Sn2S3 film. The same sample showed a highest detectivity and external quantum efficiency values of 8.70 × 109 Jones and 157 % respectively. The quick response of the detector can be affirmed from the short rise and fall time of 1.22 s and 1.21 s, respectively. Therefore, the Sn2S3 material doped with 3 % ruthenium, produced via the current economical method, emerges as a promising candidate for application in photo-detectors.

High sensitivity and low noise photodetector based on topological crystalline insulator SnTe/Si heterostructure

Topological insulators, as a class of materials with narrow bulk bandgap and gapless surface states with response wavelengths covering infrared to terahertz, have great potential for application in new generation photodetector, but the large dark current and small photocurrent limit their application, so the device performance is generally improved by the method of heterogeneous integration. SnTe, as a topological crystalline insulator with multiple surface states, has a narrower forbidden bandwidth, it is suitable for the fabrication of infrared photodetector. In this work, SnTe thin films were deposited on Si substrates by magnetron sputtering, and SnTe/n-Si heterostructure photodetectors were fabricated on this basis. The photodetector exhibited good photoresponses in the visible near-infrared (532–1400 nm), with the responsivity (R) and normalized detectivity (D*) reaching 1.12 A/W, 5.17 × 1011 Jones. Thanks to the formation of the built-in electric field at the SnTe/Si interface, the photogenerated carriers can be rapidly separated and transported, and the switching ratio reaches 103. In addition, the rise time and fall time of the device are 218 μs and 174 μs, respectively. The good performance and simple preparation method make the device have a wide application prospect in the new generation of photodetector.

Self‐Powered Broadband UV–NIR Photodetectors Based on InSe/PtS2 Van der Waals Heterostructure

AbstractVan der Waals heterostructures (vdWHs) consisting of 2D materials offer a practical and effective approach for engineering multifunctional, high‐performance photodetectors. However, 2D vdWHs photodetectors based on photoconductive effects require an external power input and are often accompanied by a large dark current, which hinders the development of miniaturization and portability of devices and greatly limits the application of devices in complex environments. Herein, a self‐powered photodetector constructed from an InSe/PtS2 vdWH with an extremely low dark current (≈10−14 A) at zero bias and a large rectification ratio of 5.1 × 103 is reported. Leveraging the robust built‐in electric field of the InSe/PtS2 vdWH, the device demonstrates pronounced photovoltaic effects, characterized by an open‐circuit voltage of 0.395 V and a substantial short‐circuit current of 37.1 nA. Remarkably, a high responsivity and detectivity of 211 mA W−1 and 8.58 × 1012 Jones, an excellent light on/off ratio of 0.8 × 107 , and a fast response time of 465/470 µs are achieved, at zero bias. The device showcases a broadband self‐powered photoresponse spanning from 265 to 1064 nm. This study demonstrates the high potential of the InSe/PtS2 vdWH for broadband self‐powered photodetector applications.

Fabrication of high-performance nanostructured CsPbI3/Si perovskite photodetector by pulsed laser deposition: Challenges and prospects

The inorganic perovskite CsPbI3 is a promising material for optoelectronic applications like photodetectors and solar cells due to its suitable bandgap and excellent properties. In this work, nanostructured CsPbI3 thin films were deposited on glass and silicon substrates by pulsed laser deposition (PLD) at laser fluences ranging from 5.7 to 10 J/cm2. Systematic characterization revealed that increasing the laser fluence significantly enhances the crystallinity, phase purity, optical emission intensity, charge carrier concentration (up to 1.38 × 1012 cm−3), and mobility (up to 164.7 cm2/Vs) of the CsPbI3 films. An optimal laser fluence of 10 J/cm2 resulted in large, elongated grains over 280 nm, tightly packed films with minimal defects, and a suitable bandgap of 1.83 eV CsPbI3/Si heterojunction photodetectors were fabricated, with the device made at 8.5 J/cm2 exhibiting maximum responsivity of 8 A/W at 600 nm, detectivity exceeding 1014 Jones, external quantum efficiency up to 17.5 × 102 %, and a high ON/OFF ratio of 225 under illumination. The photodetector performance was strongly correlated with the optimized structural order, morphology, and optoelectronic quality achieved by careful control of the laser fluence during PLD. This work highlights PLD as an effective technique for realizing high-quality CsPbI3 films with tailored properties for advanced photodetection and photovoltaic applications.

Influence of AZO buffer layer on characteristics of ZnO film on glass substrates for Schottky UV photodetector applications

An Al-doped ZnO (AZO) thin film was introduced into the structure of Ag/ZnO schottky Photo detectors (PDs) prepared by magnetron sputtering method on glass substrates. Influences of AZO layer on characteristics of ZnO film and performances of Ag/ZnO schottky PDs were discussed in detail. Results investigated by means of the scanning electron microscopy (SEM), X-ray diffraction (XRD) and Photoluminescence (PL) spectra show that the introduction of an AZO buffer layer can effectively decrease the defects and improve the crystallization of the ZnO thin film. Compared with Ag/ZnO schottky PDs, the Ag/ZnO/AZO PDs possess more excellent rectifying characteristics, the photocurrent (Iph) to dark current (Id) ratio are improved from 6.4 to 100.7. Given the bias voltage at -2 V, the photoresponsivity R and detectivity D* are increased from 0.15 A W-1 to 4.08 × 1010 Jones to 0.69AW-1 and 3.78 × 1011 Jones, respectively. The response speed becomes faster, the response and delay times are decreased from 281 to 395 ms to 178 and 300 ms, respectively. The results provide a new idea for the preparation of high performance ZnO film UV PDs on low-cost glass substrates.

Performance evaluation of SILAR deposited Rb-Doped ZnO thin films for photodetector applications

ZnO-based photodetectors (PDs) compose a remarkable optoelectronic device field due to their high optical transmittance, electrical conductivity, wide band gap, and high binding energy. This study examined the visible light photodetector performance of the pristine and Rubidium (Rb)-doped ZnO thin films. The influence of Rb doping amount (2, 4, and 6 wt% in solution) on the electrical, optical, and structural properties of the ZnO-based thin films produced by the Successive Ion Layer Adsorption and Reaction (SILAR) technique was analyzed. Structural analyses showed that all peaks correspond to hexagonal wurtzite structure with no other peak from Rb-based phases, suggesting the high quality of the crystalline pristine and Rb-doped ZnO thin films. The morphology of the thin films shows homogenous layers formed of nanoparticles where particle size was first decreased and then increased with the increasing Rb doping according to Scanning Electron Microscope (SEM) morphology analysis. Besides that, Raman spectroscopy analyses indicate that the phonon lifetimes of the ZnO-based thin films slightly increased due to the improvement of the crystal quality with the increasing amount of Rb in the SILAR solution. Photosensor measurements of the nanostructured pristine and Rb-doped ZnO thin films were measured at different light power intensities under the visible light environment. Photosensor properties were examined depending on the doping amount and light power density. In light of the literature review, our study is the first to produce Rb-doped ZnO thin films via the SILAR method, which has a promising potential for photosensor applications.Graphical

A Case Study of 2D Bi2O2Se Nanoplate Near‐Infrared Photodetectors from the Perspective of Practical Applications

AbstractOver the past several decades infrared (IR) photodetectors have received wide attention due to their important applications. 2D materials, distinguished by their unique electronic structures, ultimate dimensional confinement, and robust light‐matter interactions, provide a promising candidate for fabricating future IR photodetectors. However, there is a lack of reports concerning the practical industrial applications of these 2D photodetectors, despite that some of these 2D photodetectors have demonstrated performance exceeding that of commercial photodetectors. In this work, a case study on 2D Bi2O2Se nanoplate near‐infrared photodetectors from the perspective of practical applications is presented. With the characterization method used for nano detectors, the 2D Bi2O2Se photodetector exhibits a responsivity of 212.5 A W−1, a specific detectivity of 4.99 × 1011 Jones and an external quantum efficiency of 26 887.68% at wavelength of 980 nm, while with the traditional characterization method the photodetector shows a responsivity of 0.13 A W−1 and a specific detectivity of 2.26 × 106 Jones and an external quantum efficiency of 17.87% at wavelength of 900 nm. The Bi2O2Se nanoplate photodetector also presents good passive imaging quality in the near‐infrared wavelength region. These results suggest the great potential of Bi2O2Se nanoplate photodetectors for practical applications.

Quasi-dry layer transfer of few-layer MBE-grown MoTe2 sheets for optoelectronic applications

Achieving precise control over the growth of fully covered MoTe2 on a substrate is a crucial requirement for advancing device fabrication in the future. However, this goal continues to pose significant challenges. Thus, before the fabrication of a photodetector, we focused on optimizing a quasi-dry layer transfer process that eliminates the need for etchants and polymers. This optimization step is crucial for expanding the practicality of 2D materials in industrial applications. The transfer process, we developed can be applied to multiple 2D materials and substrates (growth/target), enabling the rapid production of elevated performance of 2D electrical devices and their van der Waals-based heterostructures. To demonstrate the effectiveness of this method, we successfully transferred MBE-grown MoTe2 on Si/SiO2 for photodetector application. The transferred MoTe2 is well characterized by various characterization tools including AFM, Raman, XPS, KPFM and UV-Vis spectroscopy. The fabricated metal semiconductor metal (MSM) photodetector on transferred MoTe2 shows the highest photoresponsivity of about 30 mA/W at low power density (0.6 μW/mm2) at an illumination source of 650 nm at a low applied voltage (3 V). The calculated detectivity of the MSM photodetector is found to be 6.56 ×1016 Jones with noise equivalent power (NEP) of 9.13 ×10−15 WHz−1/2 for this wavelength. This current research work opens the pathways to multiple research areas including optoelectronics and electronics.

High-performance solar-blind photodetector based on Si-doped α-Ga2O3 thin films grown by mist chemical vapor deposition

α-Ga2O3 has gained increasing attention in the field of photodetectors because of its wide bandgap and exceptional chemical and physical properties. Si-doped α-Ga2O3 single-crystal epitaxial films were successfully deposited on sapphire substrates using an affordable and non-vacuum-based mist chemical vapor deposition (Mist-CVD) technique. An interdigital metal-semiconductor-metal (MSM) photodetector with excellent performance was prepared by using the thin film. At 254 nm illumination and a bias voltage of 20 V, the photodetector has a high light-to-dark current ratio of 3.24×106, a responsivity of 3.23×102 A/W, a detectivity of 8.80×1015 Jones, and an external quantum efficiency of 1.58×105%. The results show that Si-doped α-Ga2O3 thin films have great potential for application in high-performance photodetectors.

Growth of Monolayer MoS2 Flakes via Close Proximity Re-Evaporation.

We report a two-step growth process of MoS2 nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS2 layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form mono- or few-layer MoS2 flakes. As a result, the close proximity re-evaporation enabled the growth of pristine MoS2 nanoflakes. Atomic force microscopy analysis confirmed the synthesis of nanoclusters/nanoflakes with lateral dimensions of over 10 μm and a flake height of approximately 1.3 nm, demonstrating bi-layer MoS2, whereas transmission electron microscopy analysis revealed triangular MoS2 nanoflakes, with a diffraction pattern proving the presence of single crystalline hexagonal MoS2. Raman data revealed the typical modes of high-quality MoS2 nanoflakes. Finally, we presented the photocurrent dependence of a MoS2-based photoresist under illumination with light-emitting diode of 405 nm wavelength. The measured current-voltage dependence across various luminous flux outlined the sensitivity of MoS2 to polarized light and thus opens further opportunities for applications in high-performance photodetectors with polarization sensitivity.

Vertical heterojunction photodetector of In2Se3/PtS2 with high polarization sensitivity and tunable electronic characteristics

A monolayer In2Se3 root number model was used with a monolayer PtS2 material 2 × 2 × 1 cell expansion to form an In2Se3/PtS2 bilayer with a lattice mismatch of 3.12 %. Utilizing first principles calculations, we systematically explore the structural, electrical, and optical characteristics of In2Se3/PtS2 heterostructures. The stabilized heterostructure displays an indirect band gap of 1.62 eV and a type I energy band arrangement. Moreover, the absorption spectra further demonstrate the heterostructure's ability to capture visible and UV light, it is significantly better than monolayer In2Se3 and monolayer PtS2, and the absorption peak at a wavelength of 185 nm is as high as 8. 07×105/cm. Using biaxial strain to change the heterojunction energy band structure, it is found that as the biaxial strain field changes, the hetero-structure of In2Se3/PtS2 transforms from a type I to a type II energy band arrangement with the applied stresses of −8 %, 2 %, 4 %, 6 %, and 8 %. Transitioning from simulations to practical applications, we model a novel photodetector based on the In2Se3/PtS2 heterojunction. Remarkably, the In2Se3/PtS2 heterojunction photodetector demonstrates high polarization sensitivity at a photon energy of 3.2 eV, boasting a maximum extinction ratio of 20, outperforming alternatives. In summary, the In2Se3/PtS2 heterostructure presents exceptional optical properties, providing a robust foundation for advanced photodetector applications.

Advances in Paper‐Based Photodetectors: Fabrications, Performances, and Applications

AbstractWith the development of wearable electronic technology, the flexible photodetectors have attracted widespread attention, and it is of great significance to develop flexible, eco‐friendly and low‐cost photodetectors. Cellulose paper, as a flexible, eco‐friendly, low‐cost, lightweight, customizable, biodegradable and renewable material, has received enthusiastic attention and rapid development in the field of photodetectors in recent years. In this review, it is focused on the research progress of paper‐based (PB) photodetectors. First, the fabrication methods of PB photodetectors are discussed, including electrode materials and optoelectronic functional materials. Then, this review systematically summarizes and analyzes the achievements of PB photodetectors on photoelectric performances (spectral response range, responsivity, detectivity, response/recovery times and on/off ratio) and flexibility characteristics (bending angle and bending cycle). In terms of key performance indicators, the PB photodetectors reported so far can detect multiple wavelengths of light from UV to near‐infrared with the maximum detectivity of 1013 Jones. In addition, the various applications of PB photodetectors is reviewed and discussed. Finally, it is look forward to the future development of PB photodetectors in terms of fabrication methods, photoelectric and flexible performances, and applications. With this review, it is hope that it will promoted the future development of PB photodetectors.

First Principle calculations for structural and optoelectronic properties of MnNi1-xAgxGe alloys: A DFT study

We investigate the optical and electronic characteristics of parental MnNiGe and doped MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) for photodetector and other electronic applications. First principles are applied to every calculation performed in the context of DFT. The generalized gradient approximation with the Hubbard potential included (GGA + U) has been chosen as the appropriate approximation to handle systems with strongly coupled electrons. The semi-metallic parental MnNiGe and doped MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) is ideal for conducting materials in electronics due to band overlapping, according to our findings. Degenerate doping of Ag into MnNiGe includes spinning the Fermi level, changing the DOS profile, and reducing the density of Fermi level states that allow tunneling from the valence band to the conduction band. An important part of this research is analyzing the refractive index, reflectivity, extinction coefficient, dielectric function, absorption coefficient, and energy loss function of parental MnNiGe and doped MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %). According to our findings, it is possible to create a photo detector based on MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) that can detect light in the visible range (below 500 nm). It has also been found that the MnNi1-xAgxGe (x = 4 %, 8 %, and 12 %) exhibits the highest sensitivity to light with a wavelength of 450 nm. Due to its advantageous optical characteristics in the visible and ultraviolet regions, this material could be useful for the development of numerous optoelectronic applications.

WS2 Nanotube Transistor for Photodetection and Optoelectronic Memory Applications.

Nanotube and nanowire transistors hold great promises for future electronic and optoelectronic devices owing to their downscaling possibilities. In this work, a single multi-walled tungsten disulfide (WS2) nanotube is utilized as the channel of a back-gated field-effect transistor. The device exhibits a p-type behavior in ambient conditions, with a hole mobility µp ≈ 1.4 cm2V-1s-1 and a subthreshold swing SS ≈ 10 V dec-1. Current-voltage characterization at different temperatures reveals that the device presents two slightly different asymmetric Schottky barriers at drain and source contacts. Self-powered photoconduction driven by the photovoltaic effect is demonstrated, and a photoresponsivity R ≈ 10 mAW-1 at 2V drain bias and room temperature. Moreover, the transistor is tested for data storage applications. A two-state memory is reported, where positive and negative gate pulses drive the switching between two different current states, separated by a window of 130%. Finally, gate and light pulses are combined to demonstrate an optoelectronic memory with four well-separated states. The results herein presented are promising for data storage, Boolean logic, and neural network applications.

Tailoring Phase Transition of Mo-S-Te Ternary System using Heat-Driven Process for Target Functionalities

Although structural engineering and phase modulation of transition metal dichalcogenides (TMDs) can be used to implement high-performance optoelectronic devices or energy cells, their expandability combined with individualized optimization for diverse applications using limited TMD materials is still challenging. Herein, we suggest an intriguing strategy to control the target functionalities of the Mo-S-Te ternary system using heat-driven crystallographic selection. The structure and phase alteration of the Mo-S-Te system can be effectively governed by modulating the thermal decomposition temperature, as evidenced by comprehensive spectroscopic and microscopic evaluations. The dual eligibility of the Mo-S-Te ternary system was validated by ascertaining the temperature-dependent selective enhancement of the optoelectronic properties or photoelectrochemical (PEC) performance as compared with those of bare MoS2. The Mo-S-Te synthesized at 300 °C exhibited superior photoresponse dynamics across various wavelengths, indicating its potential for advanced photodetection applications. In field of PEC, Mo-S-Te synthesized at 500 °C was highlighted as a promising photocathode material, offering enhanced PEC reactivity and stability. This study suggests the importance of material characteristics tailored to the synthetic conditions for target applications, which is a promising path to for the expansion of applicability in various areas using a simple approach that utilizes a limited range of TMD materials.