Semiconductor Schottky Barrier Research Articles

1.43 kV GaN-based MIS Schottky barrier diodes

In this letter, we report on a quasi–vertical GaN-based metal–insulator–semiconductor (MIS) Schottky barrier diode (SBD) with an insertion of 2 nm thick Al2O3 dielectric layer. It shows a turn-on voltage of 0.7 V, a specific on-resistance of 3.5 mΩ·cm2, and a high on/off current ratio of 1011. The proposed structure enables a breakdown voltage of 1430 V, rendering a Baliga’s power figure-of-merit of 0.58 GW cm−2. The enhanced performance is attributed to defect-related leakage can be suppressed and the direct tunneling process dominates at the MIS-based Schottky contact interface.

High-field immiscibility of electrons belonging to adjacent twinned bismuth crystals

Bulk bismuth has a complex Landau spectrum. The small effective masses and the large g-factors are anisotropic. The chemical potential drifts at high magnetic fields. Moreover, twin boundaries further complexify the interpretation of the data by producing extra anomalies in the extreme quantum limit. Here, we present a study of angle dependence of magnetoresistance up to 65 T in bismuth complemented with Nernst, ultrasound, and magneto-optic data. All observed anomalies can be explained in a single-particle picture of a sample consisting of two twinned crystals tilted by 108° and with two adjacent crystals keeping their own chemical potentials despite a shift between chemical potentials as large as 68 meV at 65 T. This implies an energy barrier between adjacent twinned crystals reminiscent of a metal- semiconductor Schottky barrier or a p-n junction. We argue that this barrier is built by accumulating charge carriers of opposite signs across a twin boundary.

Capacitance–voltage modeling of mid-wavelength infrared nBn detectors

Capacitance–voltage measurements are a powerful technique to determine doping profiles of semiconductor pn junctions and Schottky barrier diodes. The measurements were recently extended to III-V-based mid-wavelength nBn infrared detectors, and absorber doping densities have been extracted using the widely accepted Schottky approximation, where the potential drop across the device is assumed to be across the depleting absorber layer. However, this approach is limited to when the absorber region of the nBn is under high reverse bias and thus is only able to extract the absorber region doping profile. Here, we introduce a semi-analytical model that is capable of extracting barrier dopant polarity, doping concentration, and thickness, as well as contact and absorber layer doping concentrations, all from a capacitance–voltage measurement. Rather than solely considering the potential drop across the depleting layers, it considers the potential drop across the accumulating layer as well. This negative charge accumulation occurs for the contact and absorber layers in the case of reverse and forward biases, respectively. This allows for a single model to be applied to a capacitance–voltage curve at forward and reverse biases and it can provide regions of bias where the absorber transitions from depletion to accumulation. We compare the agreement of the semianalytical model with modeling results from commercially available finite element method software and experimental capacitance–voltage data. Finally, we show that the method is consistent with the Schottky approximation of extracting absorber doping densities at high reverse bias and discuss the model's limitations.

The modelling and simulation of perovskite solar cell consisting textile-based electrodes

Perovskite solar cell (PSC) consisting textile-based electrodes has been created novel features for future energy supply. Recently, Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 perovskite has appeared as a favourable candidate for flexible perovskite solar cells. However, a confined performance was acquired when the conventional Spiro-OMeTAD were used as hole transport layer (HTL) material because of suboptimal valance band offset (ΔEV) between Perovskite/HTL layers. In this study, a theoretical drift–diffusion​ modelling is used by finite volume method (FVM) to investigate performance of textile perovskite solar cell with double hole transport layers (HTLs) with graded band gap energies. Copper thiocyanate (CuSCN) and Nickel Oxide (NiO) are replaced as double HTLs, which dramatically enhanced the performance due to optimal upward step by step valance band offsets (ΔEV) between Perovskite/Textile Composite Electrode layers. It is shown that the decreasing of the metal–semiconductor schottky barrier height of electrodes leads to significant increase in fill factor (FF). Also, it is revealed that the enriching of perovskite carrier diffusion length by equipoising of carrier capture cross section, carrier total defect density and carrier thermal velocity substantially promote the overall device efficiency. The short-circuit current (Jsc) of 20.65 mA/cm 2, open-circuit voltage (Voc) of 1.19 V, fill factor (FF) of 73.57%, and power conversion efficiency (PCE) of 18.20% have been obtained by optimization of electrodes properties and perovskite layers. Remarkably, the advantageous of low cost, flexible, and chemical stable conducive textile composite, extends new opportunities in the commercial expansion of highly efficient photovoltaic textile in optoelectronic industry field.

Improved-Performance Diamond Schottky Barrier Diode With Tin Oxide Interlayer

A SnO2 thin layer was deposited between the diamond and Schottky electrode to fabricate the metal–insulator–semiconductor Schottky barrier diode (MIS-SBD). The current–voltage and current–voltage–temperature characteristics in the range from 25 °C to 150 °C of diamond SBD were investigated. The Schottky barrier height of MIS-SBD is 1.84 eV. Compared with metal–semiconductor (MS) SBD, the diamond MIS-SBD shows more stable values of barrier height and ideality factor as temperature increased. The difference in interface states density between MIS-SBD and MS-SBD is almost 2 orders of magnitude, and the breakdown voltage was increased from 102 to 123 V after introducing SnO2 layer. These results indicate that the MIS-SBD with SnO2 insulating layer shows a better performance.

A high-voltage GaN quasi-vertical metal–insulator–semiconductor Schottky barrier diode on Si with excellent temperature characteristics

In this work, a GaN quasi-vertical metal–insulator–semiconductor Schottky barrier diode (MIS SBD) on Si is demonstrated for the first time. A 4.2 nm thick SiN dielectric is adopted to suppress the reverse leakage. Both the thermionic emission current and the tunneling current under reverse bias are reduced by the SiN interlayer. As a result, the leakage of the MIS SBD is effectively reduced by more than two orders of magnitude and the breakdown voltage (BV) is improved from 121 V for a conventional SBD to 288 V for the MIS SBD. The temperature-dependent reverse I–V characteristics show high-temperature stability of the MIS SBD and the leakage maintains a very low level even at a high temperature of 400 K. In addition, the interface state density is extracted using the conductance method. The quasi-vertical MIS SBD structure exhibits an enhanced BV and excellent temperature characteristics, which indicate that this technique holds great promise for future high-power and high-temperature applications.

Room‐Temperature Processed Lateral Trench‐Metal–Insulator–Semiconductor Schottky Barrier Diodes with Amorphous Gallium Oxide (a‐Ga2O3) Thin Films on Single‐Crystal Silicon <100>

This article proposes a novel design approach for the fabrication of lateral Schottky barrier diodes (SBD) using a wide bandgap oxide semiconductor on silicon. Structural and electrical properties of the fabricated device are reported and compared with published data. The metal–insulator–semiconductor (MIS) Schottky barrier is realized between the room‐temperature sputtered Al/a‐Ga2O3 on single‐crystal <100> boron‐doped silicon substrate (p‐type). The device fabrication process is implemented entirely at room temperature. The proposed trench diode yields an ideality factor of 1.65 and a rectification ratio of ≈1 × 106 at ±5.0 V. The extracted specific ON resistance is 78 mΩ cm2, and the breakdown voltage is not observed for 180 V for a 200‐nm‐thin layer of a‐Ga2O3. Due to such low‐temperature process, simple fabrication steps, and notably high Baliga's figure‐of‐merit (BFOM), the proposed diode is, therefore, promising for power electronics applications.

Барьер Шоттки на контакте магнитного 3d-металла с полупроводником

With the aim of the Friedel transition metal d-band model and semiconductor local defect state model the analytical expressions for metal – semiconductor charge transfer and Schottky barrier height are obtained. It is shown that the account of metal magnetization leads to the increase of the charge transfer and corresponding contribution to the Schottky barrier height. Numerical estimates are made for the contacts of Co and Ni with 6H- and 4H-SiC polytypes.

Electrical Characterization of MIS Schottky Barrier Diodes Based on Nanostructured Porous Silicon and Silver Nanoparticles with Applications in Solar Cells

The accurate determination of the electrical properties of photovoltaic devices is of utmost importance to predict and optimize their overall optoelectronic performance. For example, the minority carrier lifetime and the carrier diffusion length have a strong relationship with the carrier recombination rate. Additionally, parasitic resistances have an important effect on the fill factor of a solar cell. Within this context, the alternating current (AC) and direct current (DC) electrical characteristics of Si-based metal–insulator–semiconductor (MIS) Schottky barrier diodes with the basic structure Al/Si/TiO2/NiCr were studied, aiming at using them as photovoltaic devices. The basic diode structure was modified by adding nanostructured porous silicon (nanoPS) layers and by infiltrating silver nanoparticles (AgNPs) into the nanoPS layers, leading to Al/Si+nanoPS/TiO2/NiCr and Al/Si+nanoPS+AgNPs/TiO2/NiCr structures, respectively. The AC electrical properties were studied using a combination of electrochemical impedance spectroscopy and Mott–Schottky analysis, while the DC electrical properties were determined from current–voltage measurements. From the experimental results, an AC equivalent circuit model was proposed for the three different MIS Schottky barrier diodes under study. Additionally, the most significant electrical parameters were calculated. The results show a remarkable improvement in the performance of the MIS Schottky barrier diodes upon the addition of hybrid nanoPS layers with embedded Ag nanoparticles, opening the way to their use as photovoltaic devices.

Recent advances and trend of HEV/EV‐oriented power semiconductors – an overview

This study introduces the development advances and trend of power semiconductors used in hybrid and electric vehicles (HEV/EV). The status and forecast of power electronics’ requirement in HEV/EV are discussed along with a review of the automotive standard of power semiconductor devices. The advances in automotive semiconductor technologies such as Si-based insulated-gate bipolar transistor (IGBT) and freewheeling diode (FRD) and SiC-based metal oxide semiconductor field-effect transistor (MOSFET) and Schottky barrier diode are presented. The advances in automotive semiconductor packaging technologies are illustrated from three considerations, which are the low inductance in high-power density packaging, lower thermal resistance designing, and advanced packaging technologies. The challenges and development trend of more reliable power semiconductors for HEV/EV are discussed. The challenges in Si devices are focused on power density, efficiency, reliability, and packages, while the high temperature and low inductances are the main challenges for SiC devices. Lastly, the development trend is discussed in terms of four aspects, the new generation Si IGBT for HEV/EV, such as recessed-emitter-trench, reverse-conduction-IGBT, and smart IGBT; next generation SiC MOSFET; new packaging technology and material, such as planar packaging.

AN ASSESSMENT ON ELECTRICAL CHARACTERIZATION OF Ni/n-Si SCHOTTKY RECTIFIERS WITH AND WITHOUT Ta2O5 INTERFACIAL OXIDE LAYER

We have fabricated Ni/[Formula: see text]-Si metal–semiconductor (MS) and Ni/Ta2O5/[Formula: see text]-Si metal-insulator–semiconductor (MIS) Schottky barrier diodes at room temperature and studied their current density–voltage (J–V) and capacitance–voltage (C–V) characteristic properties. The forward bias J–V characteristics of the fabricated MS and MIS devices have been evaluated with the help of the thermionic emission (TE) mechanism. Schottky barrier height (SBH) values of 0.73 and 0.84[Formula: see text]eV and ideality factor values of 1.75 and 1.46 are extracted using J–V measurements for MS and MIS Schottky barrier diodes without and with Ta2O5 interfacial oxide layer, respectively. It was noted that the incorporation of Ta2O5 interfacial oxide layer enhanced the value of SBH for the MIS device because this oxide layer produced the substantial barrier between Ni and [Formula: see text]-Si and this obtained barrier height value is better than the conventional metal/[Formula: see text]-Si (MS) Schottky diodes. The rectification ratio (RR) calculated at [Formula: see text][Formula: see text]V for the MS structure is found to be [Formula: see text] and the MIS structure is found to be [Formula: see text]. Using Chung’s method, the series resistance ([Formula: see text]) values are calculated using [Formula: see text]/[Formula: see text] vs I plot and are found to be 21,603[Formula: see text][Formula: see text] for the Ni/[Formula: see text]-Si (MS) and 5489[Formula: see text][Formula: see text] for the Ni/Ta2O5/[Formula: see text]-Si (MIS) structures, respectively. In addition, [Formula: see text] vs [Formula: see text] plot has been utilized to evaluate the series resistance ([Formula: see text]) values and are found to be 14,064[Formula: see text][Formula: see text] for the Ni/[Formula: see text]-Si (MS) and 2236[Formula: see text][Formula: see text] for the Ni/Ta2O5/[Formula: see text]-Si (MIS) structures, respectively. In conclusion, by analyzing the experimental results, it is confirmed that the good quality performance is observed in Ni/Ta2O5/[Formula: see text]-Si (MIS) type SBD when compared to Ni/[Formula: see text]-Si (MS) type SBD and can be accredited to the intentionally formed thin Ta2O5 interfacial oxide layer between Nickel and [Formula: see text]-type Si.

Device characteristics of Schottky barrier diodes using In-Ga-Zn-O semiconductor thin films with different atomic ratios

Abstract Oxide semiconductor Schottky barrier diodes (SBDs) were fabricated by using amorphous In-Ga-Zn-O (IGZO) semiconducting thin films with different atomic ratios. Higher rectification ratios and Schottky barrier heights (SBHs) were obtained when the oxygen partial pressure was high during the sputtering deposition of the IGZO films. The increase in Ga composition effectively enhanced the device characteristics, including the rectification ratio and the SBH of the SBDs. These properties were closely related to the control of oxygen vacancy concentration within the IGZO and the resulting conduction behaviors owing to Fermi-level pinning and tunneling current through the Schottky barrier. The fabricated SBD using IGZO with a higher Ga composition (In:Ga:Zn = 1.0:0.8:0.3) exhibited a rectification ratio of 8.3 × 106 and an SBH of 0.79 eV.

Highly Stable Plasmon Induced Hot Hole Transfer into Silicon via a SrTiO3 Passivation Interface

AbstractExtracting plasmon‐induced hot carriers over a metal–semiconductor Schottky barrier enables photodetection below the semiconductor bandgap energy. However, interfacial carrier recombination hinders the efficiency and stability of this process, severely limiting its implementation in telecommunication. This study proposes and demonstrates the use of epitaxially grown lattice‐matched SrTiO3 for interfacial passivation of silicon‐based plasmonic Schottky devices. The devices are activated by an electrical soft‐breakdown of the interfacial SrTiO3 layer, resulting in reproducible rectified Schottky characteristics. The transition to a low resistance state of the SrTiO3 layer boosts the extraction efficiency of hot holes upon resonant plasmonic excitation, giving rise to a two orders of magnitude higher photocurrent compared to devices with a native oxide layer. Photoresponse, tunability, and barrier height studies under reverse biases as high as 100 V present superior stability with the incorporation of the SrTiO3 layer. The investigation paves the way toward plasmon‐induced photodetection for practical applications including those under challenging operating conditions.

Lateral and Vertical Heterostructures of Transition Metal Dichalcogenides

In this paper we investigate periodic lateral and vertical heterostructures of transition metal dichalcogenides (TMDs). Lateral heterostructures are constructed by the alternating metallic and semiconducting single-layer stripes of TMDs joined commensurately along their armchair edges and attain different states depending on the widths of constituents. While these heterostructures acquire a composite character with metallic state for narrow stripes, large stripes lead to the confinement of electronic states and function as metal–semiconductor junctions with a tunable Schottky barrier. The interface or boundary between constituent stripes has finite extension and allows charge transfer between them. On the other hand, the weak van der Waals interaction between layers sets the features of vertical heterostructures. Their interfaces are sharp: metal–semiconductor junction and Schottky barrier developed thereof can be induced even within a few layers. In the absence of dopants, we find minute charge transfer ...

(Invited) Characterization of Thin Passive Film-Electrolyte Junctions. The Amorphous Semiconductor (a-SC) Schottky Barrier Approach

A detailed study of the electronic properties of thin (< 20 nm) anodic TiO2 potentiostatically grown on titanium in two different solutions is presented. The results show that the nature of the anodizing solution affects the electronic properties of the anodic film and in particular the density of electronic state (DOS) distribution. Different DOS were derived from the experimental data analyzed according to the theory of amorphous semiconductor (a-SC) Schottky barrier. It is shown that the usual non-linear and frequency dependent Mott-Schottky plots are in agreement with expected theoretical behaviour of a-SC Schottky barrier. It is shown the importance of the DOS distribution in determining the frequency response of the junction which is also related to the electrical behaviour of anodic films as “thin” or “thick” in terms of the ratio between the space-charge region and oxide film thickness.

The Amorphous Semiconductor Schottky Barrier Approach to Study the Electronic Properties of Anodic Films on Ti

A detailed study of the electronic properties of thin (<20 nm) anodic TiO2 potentiostatically grown on titanium in two different solutions is presented. The results show that the nature of the anodizing solution affects the electronic properties of the anodic film and, more specifically, the density of electronic states (DOS) distribution. Different DOS were derived from the experimental data analyzed according to the theory of amorphous semiconductor (a-SC) Schottky barrier. It is shown that the usual non-linear and frequency dependent Mott-Schottky plots are in agreement with expected theoretical behavior of a-SC Schottky barrier.

(Invited) Characterization of Thin Passive Film-Electrolyte Junctions. Amorphous Semiconductor (a-SC) Schottky Barrier Approach

The knowledge of the solid-state properties of passive film is a preliminary task for a full understanding of the electron and ion transfer processes at the metal/oxide and oxide/electrolyte interface. Both processes are of paramount importance in determining the mechanism of film growth and dissolution as well as in determining the nature of the breakdown during the growth of anodic oxide films or the onset of generalized or localized corrosion process (1-2). With very few exceptions, it is a common belief, that most of anodic oxide films, grown on metals and alloys in aqueous solutions, display a semiconducting or insulating behaviour. It is also very well known that in many cases the initial air-formed or electrochemically grown films have a highly defective or amorphous structure. In any case the location of the characteristic energy levels of the metal/passive-film/electrolyte junction is a necessary task to reach a deeper understanding of the mechanism of charge transfer at the metal/oxide/electrolyte interface so that it is not surprising that in-situ electrochemical techniques like electrochemical impedance spectroscopy (EIS) and differential admittance (DA) have been routinely employed to get information both on the electrical properties as well as on the mechanism of growth of thin and thick oxide films. In order to account for the amorphous or scarcely crystalline nature of anodic oxide films we have suggested, in several papers (3-5), an approach to the description of physicochemical properties of semiconducting passive films based on the theory of amorphous semiconductors. We have stressed in previous papers that the characterization of semiconducting passive film/electrolyte junction based on the use of simple M-S theory to get information on the solid state properties of anodic films presents some drawbacks in terms of assumptions as well as for a correct location of the characteristics energy levels of the passive film/electrolyte junction: flat band potential, Ufb, and the nearest characteristic level of the semiconductor EC (n-type SC) or EV (p-type SC). In an attempt to overcome the intrinsic limits of this traditional approach we advocated the use of the theory of a-SC Schottky barrier as developed in (6-10). In more recent papers (4-5) we try to extend the results of the a-SC Schottky barrier theory to the case of thin film amorphous semiconductors, i.e. when the space charge region of the semiconductor reaches an extension near to the 70% of the film thickness. In the last paper (5b) we introduced also a new parameter directly related to the series resistance of the space charge region which allows to extract information on the homogeneity of the DOS distribution within the space charge region as well as on the relative weight of the volumetric charge presents in the semiconductor with respect to the surface charge located on the metal. Although some very preliminary results strongly supported the novel proposed approach to the use of a-SC theory for thin semiconducting film, a more detailed experimental study was undertaken in order to exploit the robustness of our approach to the case of thin semiconducting anodic films. In this work the results of an extensive characterization, by means of EIS and DA technique, of thin semiconducting passive films grown on Ti metal will be presented in order to highlight the validity of the proposed approach. Further information on the amorphous nature and on the possible dependence of the dielectric constant on the electric field will be taken into account in an attempt to rationalize the complex behaviour of barrier-like passive film on Ti. References 1 - F. Di Quarto, M. Santamaria, Corrosion Eng. Sci. Tech. 39 (2004) 71. 2 - Harrington, S.P. and Devine, T.M., J. Electrochem.Soc. 155 (2008) C381. 3 - F. Di Quarto, F. La Mantia, M. Santamaria, Electrochim. Acta 50 (2005) 5090. 4 - F. La Mantia, H. Habazaki, M. Santamaria, F. Di Quarto, Russ. J. Electrochem 46 (2010) 1306. 5 - a) F. La Mantia, J. Stojadinovic, M. Santamaria, F. Di Quarto, ChemPhysChem, 13 (2012) 2910; b) F. La Mantia, M. Fan, J. Stojadinovic, M. Santamaria, S. Miraghaei, F. Di Quarto, Electrochim. Acta 179 (2015) 460. 6 - R.A. Abram, P.J. Doherty, Phil. Mag. B 45 (1982) 167. 7 - I.W. Archibald, R.A. Abram, Phil. Mag. B 48 (1983) 111. 8 - I.W. Archibald, R.A. Abram, Phil. Mag. B 54 (1986) 421. 9 - J.D. Cohen, D.V. Lang, Phys. Rev. B 25 (1982) 5321. 10 - D.V. Lang, J.D. Cohen, J.P. Harbison, Phys. Rev. B 25 (1982) 5285.

Plasmon‐Induced Sub‐Bandgap Photodetection with Organic Schottky Diodes

Organic materials for near‐infrared (NIR) photodetection are in the focus for developing organic optical‐sensing devices. The choice of materials for bulk‐type organic photodetectors is limited due to effects like high nonradiative recombination rates for low‐gap materials. Here, an organic Schottky barrier photodetector with an integrated plasmonic nanohole electrode is proposed, enabling structure‐dependent, sub‐bandgap photodetection in the NIR. Photons are detected via internal photoemission (IPE) process over a metal/organic semiconductor Schottky barrier. The efficiency of IPE is improved by exciting localized surface plasmon resonances, which are further enhanced by coupling to an out‐of‐plane Fabry–Pérot cavity within the metal/organic/metal device configuration. The device allows large on/off ratio (&gt;1000) and the selective control of individual pixels by modulating the Schottky barrier height. The concept opens up new design and application possibilities for organic NIR photodetectors.

Improvement of 4H-SiC Epitaxial Layers Grown on 2&lt;sup&gt;o&lt;/sup&gt; Offcut Si-Face Substrates

The surface quality of epitaxial layers grown on 2° offcut substrates was improved. These substrates require a lower growth temperature and a lower C/Si ratio than their 4° offcut counterparts to suppress macro step bunching. Surface morphology, triangular defect density, and doping uniformity presented a trade-off relationship with respect to growth parameters. The implementation of a low C/Si ratio buffer layer led to a balance between surface defect density, which reached a minimum of 0.2 cm−2, and good doping uniformity on an equivalent wafer size (150 mm). An evaluation of metal–oxide–semiconductor capacitors and Schottky barrier diodes fabricated on 2° offcut epitaxial layers showed that the quality of these epitaxial layers was satisfactory for application in devices.

Recent progress in Ga2O3 power devices

This is a review article on the current status and future prospects of the research and development on gallium oxide (Ga2O3) power devices. Ga2O3 possesses excellent material properties, in particular for power device applications. It is also attractive from an industrial viewpoint since large-size, high-quality wafers can be manufactured from a single-crystal bulk synthesized by melt–growth methods. These two features have drawn much attention to Ga2O3 as a new wide bandgap semiconductor following SiC and GaN. In this review, we describe the recent progress in the research and development on fundamental technologies of Ga2O3 devices, covering single-crystal bulk and wafer production, homoepitaxial thin film growth by molecular beam epitaxy and halide vapor phase epitaxy, as well as device processing and characterization of metal–semiconductor field-effect transistors, metal–oxide–semiconductor field-effect transistors and Schottky barrier diodes.