Metal-semiconductor-metal Research Articles

Self-Healing Supramolecular Flexible Network of Zn(II): Exploring Chemo-Responsiveness, Antimicrobial Efficiency, and Variable Microelectronic Device Performances.

The Zn(II)-supramolecular metallogel (i.e., Zn-Py) of 2,6-pyridinedicarboxylic acid was prepared through the addition of a metal source and 2,6-pyridinedicarboxylic acid as a low molecular weight gelator. The Zn-Py metallogel encapsulated N,N'-dimethylformamide as gel-immobilized polar aprotic solvent media. The mechanical features of the synthesized metallogel were investigated. The thixotropic behavior of the Zn-Py metallogel was also analyzed. The microscopic feature of the metallogel was imaged through FESEM and TEM studies. The EDS pattern of the metallogel ratified the role of different gel-building chemical constituents. The stimuli responsiveness of the metallogel was also tested. The metallogel-forming mechanistic protocol was visualized through FTIR and ESI mass spectroscopic analyses. The bioeffectiveness, i.e., antimicrobial potency, of Zn-Py was also studied. The antimicrobial efficiency against both Gram +ve and Gram -ve bacteria including Salmonella typhimurium (MTCC 98), Escherichia coli (MTCC 1667), Bacillus cereus (ATCC 13061), Listeria monocytogenes (MTCC 657), and Staphylococcus aureus (MTCC 96) was critically analyzed. The FESEM images of the live bacteria and damaged bacteria due to the action of the metallogel were experimentally investigated. The Zn-Py metallogel was also used to fabricate the heterojunction and Schottky-type photodetectors to show their excellent light-matter interaction and their potentiality as active material in optoelectronics. The electrical parameters of semiconductor diodes such as the p-n junction and Schottky diode fabricated by the synthesized Zn-Py metallogel were investigated. Outcomes of the experimental investigation demonstrated that the tested metallogel effectively showed p-n junction diode parameters, especially with the ideality factor (η) of 1.3 under a dark environment. This fabricated device efficiently depicted a great ON/OFF ratio of 33.4 at a reverse bias voltage of -2 V. The metal-semiconductor-metal (M-S-M) junction-type Schottky barrier diode was also fabricated using the Zn-Py metallogel where the Au/Zn-Py metallogel/Au-based device fabrication strategy was implemented.

Influence of high-k La2O3 interfacial oxide layer on the performance of GaN based Schottky barrier ultraviolet-B and A photodetection sensors

GaN based metal-semiconductor-metal (MSM) type Schottky heterojunction-based ultraviolet (UV) photodetectors (PDs) have already proven as an efficient candidate for photodetection applications. However, in real time applications, GaN based MSM type UV PD device display higher dark current, weak signal detection and required external bias are seriously limiting their usage. Therefore, self-powered interdigitated electrode type Cr/Cu/La2O3/GaN: MIS (metal-insulator-semiconductor) heterojunction visible blind UV PD has been fabricated and studied in UV-B and A region. The structure, morphology, chemical and optical parameters of La2O3 films were evaluated using GIXRD, AFM, XPS and UV–Vis techniques, respectively. The reported interdigitated Cr/Cu/La2O3/GaN: MIS UV PD device yielded a higher Schottky barrier height (SBH) of 0.95 eV (dark) and 0.89 eV (360 nm) indicating the formation of higher potential barrier. At an applied bias of 0 V, the fabricated GaN MIS PD yielded an UV to visible rejection ratio (R360/R400) of 1.62 × 102. In UV-A region (at 0 V of 360 nm), the fabricated Cr/Cu/La2O3/GaN: MIS UV PD device exhibited a peak responsivity of 28.9 mAW−1, D∗ of 3.57 × 1012 Jones and EQE of 19.2 %. On the other hand, in UV-B region (at 0 V of 310 nm) the MIS UV PD device exhibited a peak responsivity of 34.4 mAW−1, D∗ of 4.2 × 1012 Jones and EQE of 22.7 %. During 360 nm illumination (at 0 V), the temporal response measurements of GaN UV PD device yielded the best rise/fall times of 70 ms/141 ms. This work validates the fact that the high-k La2O3 thin film as an interfacial oxide layer at the metal/GaN interface provides a novel solution for the photo detection field in the self-powered mode i.e., without any external bias.

Photoresponse characteristics of bulk gallium nitride schottky barrier metal-semiconductor-metal ultraviolet photodetectors

In this work, bulk gallium nitride (GaN) Schottky barrier metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors (PDs) were fabricated, and their key performance metrics such as photoresponse, photosensitivity, gain, external quantum efficiency, detectivity, noise equivalent power, rise time, and fall time were thoroughly evaluated. The Schottky barrier was formed using platinum (Pt) metal with two different sizes of interdigitated electrode on the bulk GaN samples.The effects of mask size on the photoresponse characteristics were investigated. The Pt/bulk GaN MSM UV PDs exhibited outstanding performance under 365 nm UV light. At a bias voltage of 5 V, the PDs with smaller active areas (0.238 cm²) achieved a responsivity of 13.6 mA/W and a fast rise time of 174 ms, while those with larger active areas (0.412 cm²) demonstrated a responsivity of 2.62 mA/W and a rise time of 286 ms. Even at 0 V bias, these devices showed responsivities of 1.34 µA/W and 3.40 µA/W for the small and large masks, respectively, indicating that they possess self-powered device capabilities.

All‐Electronic Memristor Based on Charge Carrier Confinement in Bulk Semiconductor of Metal–Semiconductor–Metal Structure

AbstractMemristors have gained significant attention in recent years due to their potential applications in computing and memory technology by offering higher performance, lower power consumption, and increased storage capacity. In this paper, a new type of volatile memristor is presented by analyzing the dynamic behavior of charge carriers within a metal–semiconductor–metal (MSM) structure. It is shown that an all‐electronic memristor is achieved through the confinement of majority charge carriers within the bulk semiconductor by the favor of high barrier Schottky contacts. The findings reveal a remarkable current offset between forward and backward scans, along with exceptional current pulse consistency with a tunable current level using pulse frequency. These characteristics greatly simplify the process of designing electrical circuits incorporating this memristor variant. Furthermore, this research paves the way for the development of crystalline semiconductor‐based memristors. While various semiconductors with controllable doping densities can be considered as potential candidates for this type of memristor, the calculations using silicon demonstrate the integration of this semiconductor with the current technology holds significant promise for two terminal memristors.

Facile assembly of SnO2 thin film-based Al/SnO2/Al device for sensing of 260 nm UVC and 365 nm UVA radiation

An Al/SnO2/Al metal-semiconductor-metal (MSM) device was formed by depositing a ∼55 nm thin film of SnO2 on Si substrate. Structural, surface morphology and optical properties of the SnO2 film were studied. The current-voltage (I-V) characteristics of the device were recorded under the dark condition followed by 260 nm-UVC and 365 nm-UVA illumination conditions. Under the dark condition, the device shows a resistivity of 8.05 Ωcm at V=1.5 V bias voltage. The device produces nearly symmetric rectifying-type I-V characteristics under forward and reverse bias conditions. The electrical properties of the device were explained using back-to-back Schottky diode model. Under the dark condition, the ideality factor of the junction under forward and reverse bias were estimated to be 1.08 and 1.72 respectively. The external quantum efficiency of the device under UVC was found to be ∼518.72 % and specific detectivity reached as high as 1.03×109 Jones at 2.0 V with a response time of ∼1 s. The device showed a high signal-to-noise ratio between 0.5 and 1.5 V bias voltages. The values of the ideality factor being greater than 1 was attributed to the presence of point defects in the SnO2 layer as verified by photoluminescence study. This study reveals that the device could be used as a UVC and UVA sensor at a relatively low bias voltage of ∼1.5 V.

4H-SiC ultraviolet photodetector array with vertical MSM configuration

Abstract The increasing demand for ultraviolet (UV) imaging in extreme conditions, such as high temperatures and strong radiation, has spurred advancements in UV photodetector arrays. Traditional metal-semiconductor- metal (MSM) 4H-SiC UV photodetector array, with their planar structure and M×N electrode connections, face challenges in circuit design. Our research utilizes a vertical design for building the photodetector array, reducing the connections to just M+N, thereby simplifying the circuit design and signal processing. Utilizing semi-insulating 4H-SiC wafer and TiN electrodes, we developed an 8×8 vertical MSM photodetector array. Tested under a 365 nm light source at 10.5 mW/cm2 and a 5V bias, the array demonstrated low dark currents, high contrasts under illumination, and a 100% operational yield. With average photo current and dark currents of 1.56×10-8 A and 2.94×10-13 A, respectively, the average photo-to-dark current ratio (PDCR) exceeded 5×104 Our design effectively minimized sneak path currents and achieved a low crosstalk rate of 0.46%, enabling the capture of clear, high-contrast images. This marks a significant advancement in the application of MSM 4H-SiC UV photodetectors for imaging in extreme conditions.

Enhanced UV photodetector using Mg-doped ZnO sub-micro tube films synthesized through laser-assisted chemical bath growth

This study presents the fabrication of MgxZn(100-X)O thin films (TFs) with Mg concentration levels (x) of 0.5 at%, 1.0 at%, 1.5 at%, and 2.0 at% on glass substrates using the novel laser-assisted chemical bath growth (LACBG) method, aimed at investigating their photo-response for potential UV photodetector applications. Utilizing a continuous wave semiconductor laser with a 444.5 nm wavelength, 1 W power, and 6 min of irradiation, the LACBG method successfully produced high-quality Mg-doped ZnO TFs. These films were deposited on glass substrates coated with silver (Ag) to serve as electrode contacts for constructing a metal-semiconductor-metal (MSM) UV photodetector. The structural, optical, and electrical properties of the TFs were thoroughly analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to examine the crystal microstructures and surface morphologies, revealing vertically aligned hexagonal symmetrical sub-micro tubes. In contrast, energy dispersive X-ray (EDX) analysis confirmed successful Mg incorporation into the ZnO lattice. UV–visible absorbance spectra indicated a blue shift in the absorption edge and increased band gap energy from 3.24 eV to 3.67 eV with rising Mg content. The UV photodetectors, particularly those with 2.0 at% Mg-doped ZnO TFs, demonstrated significantly enhanced UV responsiveness attributed to optical confinement, high surface-to-volume ratio, and superior structural quality. Performance metrics for the 2.0 at% Mg-doped ZnO TFs included a responsivity of 10.60 A/W, external quantum efficiency of 34.10, specific detectivity of 2.25 × 107 Jones, noise equivalent power of 5.34 × 10−11 W, rise time of 86.9 ms, and decay time of 324.4 ms. These findings underscore the potential of Mg-doped ZnO TFs for high-performance UV photodetection applications. The novelty of this study lies in utilizing LACBG to achieve high-quality Mg-doped ZnO TFs, offering a cost-effective, low-temperature method that enhances UV photodetector performance.

Enhancement of photoresponse for InGaAs infrared photodetectors using plasmonic WO3-x/CsyWO3-xnanocrystals.

Fast and accurate detection of light in the near-infrared (NIR) spectral range plays a crucial role in modern society, from alleviating speed and capacity bottlenecks in optical communications to enhancing the control and safety of autonomous vehicles through NIR imaging systems. Several technological platforms are currently under investigation to improve NIR photodetection, aiming to surpass the performance of established III-V semiconductor p-i-n (PIN) junction technology. These platforms include in situ-grown inorganic nanocrystals and nanowire arrays, as well as hybrid organic-inorganic materials such as graphene-perovskite heterostructures. However, challenges remain in nanocrystal and nanowire growth, large-area fabrication of high-quality 2D materials, and the fabrication of devices for practical applications. Here, we explore the potential for tailored semiconductor nanocrystals to enhance the responsivity of planar metal-semiconductor-metal (MSM) photodetectors. MSM technology offers ease of fabrication and fast response times compared to PIN detectors. We observe enhancement of the optical-to-electric conversion efficiency by up to a factor of ~2.5 through the application of plasmonically-active semiconductor nanorods and nanocrystals. We present a protocol for synthesizing and rapidly testing the performance of non-stoichiometric tungsten oxide (WO3-x) nanorods and cesium-doped tungsten oxide (CsyWO3-x) hexagonal nanoprisms prepared in colloidal suspensions and drop-cast onto photodetector surfaces. The results demonstrate the potential for a cost-effective and scalable method exploiting tailored nanocrystals to improve the performance of NIR optoelectronic devices.

One-step solution processing of printable Sb2S3 nano-rods for high-performance photoconductors

Abstract Achieving large-scale, affordable, and highly dependable production of antimony sulfide is crucial for unlocking its potential in various applications, including photoconductors, solid-state batteries, thermoelectrics, and solar cells. In our study, we introduce a straightforward, economical, and catalyst-free single-step solution process for fabricating one-dimensional Sb2S3 nanostructures on flexible polyimide substrates, and we explore their use as photoconductors in the ultraviolet (UV) and visible light spectrum. The precursor solution for creating the Sb2S3 films is prepared by dissolving specified quantities of elemental Sb and S in a solution mixture of ethylenediamine and 2-mercaptoethanol. This solution is then spin-coated onto a polyimide substrate and subsequently annealed at 300 °C for several minutes. Utilizing field emission scanning electron microscopy, grazing incidence x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we demonstrate that the Sb2S3 films possess high crystallinity, uniform morphology, and a composition that is nearly stoichiometric. Additionally, through Tauc plot analysis, we determine that the films exhibit a direct bandgap of approximately 1.67 eV, which is in close agreement with the bandgap predicted by Heyd–Scuseria–Ernzerhof (HSE06) density-functional theory simulations. The metal-semiconductor–metal photoconductors fabricated with these films display a significant photoresponse to both UV and visible light. These devices achieve a UV on/off ratio of up to 160 at a light intensity of 30 mW cm−2, with brief rise and fall times of 44 ms and 28 ms, respectively.

Metal-semiconductor-metal UVA photodetector based on TiO2 thin films synthesized via liquid phase deposition method

In this work, titanium dioxide (TiO2) thin film-based metal-semiconductor–metal (MSM) ultraviolet (UV) photodetectors (PDs) were fabricated on glass substrates via liquid phase deposition (LPD) technique at various deposition time in the range of 3–6 h. Varying deposition time significantly impacted the physical properties of the films. Increasing the deposition time revealed a mixture of clusters and hexagonal-like structures in film’s morphology. The energy band gap of the TiO2 films decreased from 3.30 to 3.09 eV upon increasing the deposition time. Photodetection characteristics were examined by exposing the MSM UV PD to 390 nm UV light with an intensity of 1.6 mW cm−2 and a bias voltage of 5 V. The fabricated PDs implied characteristics of I-V ohmic contact. The optimum photodetection characteristics were achieved for TiO2 film deposited at 6 h which exhibited 36.9 μA maximum photocurrent, 20080.3% sensitivity, 201.80 gain, 225 mA W−1 responsivity, 81.07% external quantum efficiency, 0.276 s response time, and 0.274 s recovery time. The photoelectric properties of the films were strongly affected by the increased grain size and improved crystallinity of the films due to the prolonged deposition time. The optimum film demonstrated its potential to be a promising candidate for UV PD applications.

High ultraviolet gain in Ga2O3/ZnO heterojunction photodetector based on MSM structure

Amorphous Ga2O3 (a-Ga2O3) has attracted extensive attention due to its simple preparation process and low cost, but the extension of photoelectron lifetime caused by the trap state inhibits the responsiveness of a-Ga2O3 photodetector (PD), and how to improve the ultraviolet (UV) gain of a-Ga2O3 based PD is still a challenge. In this study, an a-Ga2O3/ZnO heterojunction PD based on metal-semiconductor-metal (MSM) structure was designed and fabricated by radio frequency magnetron sputtering (RFMS), and a high-concentration electron transport channel was formed by using carrier multiplication and specific band structure in the high-field region of MSM structure, which achieved high optical gain and extraordinary optical detection ability. In the UVC-UVA band, the device has a peak responsivity of 1.59 A W−1 and a high light-dark ratio, EQE and D* of 1×104, 647 % and 3.6×1012 Jones under 5 V, respectively. In particular, compared to ZnO PD and a-Ga2O3 PD, the responsivity of the device is improved by a factor of 21 and 90, respectively. This study provides a new and effective method for the significant improvement of a-Ga2O3 based UV photoelectric detection performance.

Characterization of composition dependence of properties of a MgNiO-based MSM structure

In this study, the effect of Mg composition on structural and optical properties of MgxNi1-xO alloy thin film single crystal semiconductors as well as their implementation into Metal-Semiconductor–Metal (MSM) photodetector are studied. An 850 meV blue-shift of the bandgap is observed from 3.65 eV to 4.50 eV with increasing Mg composition from 0% to 67%. The deep ultraviolet/visible rejection ratio, which is the ratio of photosensitivity at a peak wavelength of 360 nm to that at 450 nm is found to be ∼58 for Mg composition of 67%. Mg rich (%67 Mg) alloy-based photodetector is found to have two orders smaller dark current and have higher spectral response compared to NiO-based one. Spectral responsivities for MgxNi1-xO photodetectors are determined as 415 mA W−1, 80 mA W−1, and 5.6 mA W−1 for Mg compositions of 67%, 21%, and 0% (reference-NiO), respectively. Furthermore, the detectivity of the photodetectors enhances as Mg composition increases and the highest detectivity of a magnitude of ∼1011 Jones is found for the photodetector with Mg composition of 67%.

Investigating the role of Ag-doped ZnO thin films in UV photodetectors produced via laser assisted chemical bath growth technique

This study introduces the innovative fabrication of Ag-doped ZnO thin films (AgxZnO(100−x) TFs) with varying silver (Ag) concentrations (x) of 0.5, 1.0, 1.5, and 2.0 at% on glass substrates using a simple and cost-effective method known as laser-assisted chemical bath growth (LACBG). This process aims to create metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors. A continuous wave semiconductor laser with a 444.5 nm wavelength, 5 W power, and 6 min irradiation time was employed to synthesize high-quality Ag-doped ZnO TFs on the glass substrate. Ag electrodes were utilized as Schottky contacts to form MSM UV photodetectors. Structural and morphological analyses conducted using XRD and SEM revealed vertically aligned nanorods and nanoflowers with a high c-axis orientation and hexagonal wurtzite facets, while EDX confirmed Ag incorporation into the ZnO lattice. The UV–Visible absorbance spectra indicated a decrease in bandgap from 3.28 to 2.84 eV with increased Ag content. The current-voltage (I–V) characteristics of the Ag-doped ZnO TFs UV photodetector showed significantly enhanced conductivity at a 2.0 at% concentration level, achieving a responsivity of 10.78 A/W, an external quantum efficiency of 34.67 % at −3 V bias voltage. Finally, the modified device exhibited a sensitivity of 14661.9 %, a gain of 147.62, and a detectivity of 2.25 ×107 Jones, demonstrating its suitability for optoelectronic 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.

Self-powered broadband photodetectors based on Bi2O2Se with asymmetric contact areas

Self-powered broadband photodetectors are widely used in military reconnaissance, outdoor environmental sensing, wearable medical monitoring. Current commercial broadband photodetectors based on conventional materials are structurally complex, high cost, and external power consumption. 2D materials emerge as promising candidates for the development of novel photodetectors with superior performances. The construction of self-powered photodetectors predominantly employs the heterostructures or metal–semiconductor–metal (MSM) configurations, which still suffer from either multiple steps of material growth, transferring, alignment or various photolithography, film deposition techniques. Herein, a simple and effective asymmetric contact strategy is proposed to fabricate Bi2O2Se-based self-powered broadband photodetectors with asymmetric Au contact areas. The photodetector exhibits excellent performance under 350–1150 nm illumination. The responsivity is as high as 1.38, 4.76, and 0.63 A/W under 350, 550, and 1050 nm, respectively, which are much higher than those of the previously reported self-powered photodetectors based on Bi2O2Se nanosheets. Meanwhile, the self-powered photodetector has a high external quantum efficiency of 1073.16 % at 550 nm. In addition, the photodetector has excellent stability in the air and enables both imaging and optical communication. Owing to the simple architecture, cost-effectiveness, straightforward manufacturing process, and impressive performance, the proposed self-powered photodetectors hold considerable promise for future applications.

Enhancement of the response speed of CIGS-based photodetector by Te-doping

Cu(In,Ga)Se2 (CIGS) based devices are promising candidates for high performance photodetector applications. The present work investigated the effects of Te-doping on the properties of CIGS layers and studied the performance of photodetectors (PDs) fabricated on these films. The films were vacuum evaporated on glass substrates and their morphological, structural and optical properties were evaluated after an annealing step at 550ºC. Morphological data indicated that undoped CIGS films had non-uniform surface features with large grains separated by nanoparticles. Addition of 6.6 % Te improved the morphology and yielded a smoother layer. Further increase in Te concentration showed appreciable reduction in surface feature size and shape. X-ray diffraction patterns showed that increasing the Te amount in CIGS caused a shift in the XRD peaks towards smaller angles pointing to replacement of Se atoms by Te. Peak splitting at higher Te samples suggested a graded structure with Se and Te amounts changing through the thickness of the film. Raman analysis demonstrated formation of CuInGa(Se,Te)2 (CIGST) compound. According to Tauc’s approximation, CIGS films with and without Te atoms possessed two energy band gaps of Eg1 and Eg2 that were in the ranges of 1.10–1.28 eV and 1.16–1.36 eV, respectively. Electrical data obtained from photodetector devices showed a responsivity of 4.44×10−1 A/W and a detectivity of 8.01×107 Jones for Te-free material, while the rise/fall times were measured as 34/148 ms. A much faster response speed of 19/20 ms was reached for devices fabricated on films with 10.2 % Te. This work demonstrated, for the first time, the fabrication low-cost and high-performance metal-semiconductor-metal (MSM) type CIGST-based PDs.

Terahertz Radiation Detectors Using CMOS Compatible SOI Substrates

AbstractIn recent years, silicon‐based room temperature Terahertz (THz) detectors have become the most optimistic research area because of their high speed, low cost, and unimpeded compatibility with mainstream complementary metal‐oxide‐semiconductor (CMOS) device technologies. However, Silicon (Si) suffers from low responsivity and high noise at THz frequencies. In this review, the recent advances in Si‐based THz detectors using silicon‐on‐insulator (SOI) substrates are presented. These offer several advantages over bulk counterparts, such as reduced parasitic capacitance, enhanced electric field confinement, and improved thermal isolation. The different types of THz detectors exploiting SOI substrate, such as conventional metal‐oxide‐semiconductor field effect transistors (MOSFETs), junction‐less MOSFETs, junction‐less nanowires field effect transistors (JLNWFETs), micro‐electromechanical system (MEMS), metal‐semiconductor‐metal (MSM) structures, and single electron transistor (SET), are discussed, and their key performances in terms of responsivity, noise equivalent power (NEP), bandwidth, and dynamic range are compared. The challenges and opportunities for further improvement of SOI THz detectors, such as device scaling, integration, and modulation, are also highlighted. This review may offer compelling evidence supporting the idea that SOI THz detectors have the potential to facilitate high performance, low power consumption, and scalability—qualities essential for advancing next‐level technologies.

Preparation of Sn-Doped Ga2O3 Thin Films and MSM Ultraviolet Detectors Using Magnetron Co-Sputtering.

Sn-doped Ga2O3 thin films and metal-semiconductor-metal (MSM) ultraviolet detectors were prepared using the co-sputtering method to enhance their photoelectric performance. The results revealed that Sn doping can effectively change the optical and electrical properties of thin films, greatly improving the photoelectric responsiveness of the devices. Through microstructure testing results, all of the thin film structures were determined to be monoclinic beta phase gallium oxide. At a DC power of 30 W, the thickness of the Sn-doped thin film was 430 nm, the surface roughness of the thin film was 4.94 nm, and the carrier concentration, resistivity, and mobility reached 9.72 × 1018 cm-3, 1.60 × 10-4 Ω·cm, and 45.05 cm3/Vs, respectively. The optical results show that Sn doping clearly decreases the transmission of thin films and that the bandgap can decrease to 3.91 eV. Under 30 W DC power, the photo dark current ratio of the detector can reach 101, time responses of tr = 31 s and tf = 22.83 s were obtained, and the spectral responsivity reached 19.25 A/W.

High-performance transparent AZO UV photodetectors

In this work, the fabrication of undoped ZnO (ZO) and 3 at.% aluminum (Al) doped ZnO (AZO) thin films (TFs) based transparent photodetectors (PDs) was reported. Both films were spin-coated on fluorine-doped tin oxide (FTO) substrates to investigate the influence of Al doping on the ultraviolet (UV) detection performance of the devices. The systematic characterizations reveal that Al doping positively affects the characteristics of ZO-TFs. The Al doping leads to slight shift in crystalline peaks and induces an enhancement in grain size. In addition, the surface roughness of ZO-TFs gets lower on Al doping. Further, the Al doping improved the transparency and widening of band gap of TFs. The PDs having metal–semiconductor-metal (MSM) configuration were achieved by screen-printing of Ag paste onto ZO and AZO-TFs. The current–voltage (I-V) profiles of the fabricated PDs were measured in the dark and under UV excitation of 365 nm. The AZO-TFs based MSM PD exhibits a spectral responsivity of 326.82 mA/W and an external quantum efficiency of 111.03%. The reproducibility of the fabricated PDs was tested by performing time-dependent photo-response measurements.