Electronic Properties Of Semiconductors Research Articles

Gas sensitivity evaluation of decomposition gases in environmentally friendly insulating devices (C4F7N/CO2) (Chromium cluster-modified BNNTs surface interface at the atomic scale)

Under the global trend of green development, the research and development of environmentally friendly gas-insulated electrical equipment and the associated technical issues in the power systems industry have become important research topics. This study investigates the monitoring technology for decomposition gases (CO, C2F6, and COF2) under insulation defect conditions in environmentally friendly GIS equipment based on the green insulating gas mixture C4F7N/CO2. Initially, chromium clusters (Crn, n = 1–4) were used to modify one-dimensional boron nitride nanotubes (BNNTs), describing the changes in semiconductor electronic properties and magnetism at the microscopic interface. Interestingly, the electronic properties of the system changed significantly after modification, with increased electron mobility and enhanced conductivity. Subsequently, adsorption tests were conducted on three potential target gases, revealing that Cr-BNNT exhibited excellent adsorption for COF2, with an adsorption energy reaching -9.555 eV. This indicates its potential as a clean material for addressing COF2 (toxic) and CO leaks. Lastly, and most importantly, in the assessment of sensing performance, it has been discovered that Cr-BNNT holds promise as a gas sensor for C2F6. Furthermore, to meet diverse sensing requirements and environmental conditions, Cr3-BNNT and Cr4-BNNT have demonstrated potential as sensor array materials for the detection of CO (300 K, 0.145 μs) and COF2 (500 K, 3 min) gas concentrations, respectively. Our study contributes to the advancement of novel eco-friendly insulating gases and explores the use of new materials for monitoring the insulation performance and condition assessment of environmentally friendly GIS equipment.

CaCl2 doping effect on optical and structural properties of halide perovskites under ligand assisted reprecipitation synthesis

The high potential of metal halide perovskite (MHP) nanocrystals with the general formula CsPbX3 (X = Cl, Br, and I) has led to the development of easy and cost-effective methods on a daily basis. The room temperature (RT) and open atmosphere ligand-assisted reprecipitation (LARP) methods were utilized to synthesize CsPbBr3 and CsPbBr2I nanocrystals (NCs). CaCl2 was used as a dopant in four different concentrations (0.25, 0.5, 0.75, and 1 % molar) to optimize the optical and electrical properties and to enhance the stability of NCs. The most optimal results were observed with 0.25 % doping for CsPbBr2I and 0.75 % doping for CsPbBr3. XRD and FE-SEM analyses revealed a cubic crystal structure for the synthesized nanocrystals. Dynamic light scattering (DLS) analysis indicated an average size of was 35–70 nm. The introduction of Ca2+ impurity, resulted in increased sizes for 0.75 % doped CsPbBr3 NCs; and increased intensity for 0.25 % doped CsPbBr2I NCs. Optical studies, including UV–vis, Fourier Transform Infrared (FTIR), and photoluminescence spectroscopies were conducted. The bandgap of CsPbBr2I and CsPbBr3 was estimated at 2.60 and 2.75 eV, respectively. The FTIR spectra suggested the effective involvement of the ligand agents oleic acid (OA) and oleylamine (OLA) in synthesis of metal halide perovskite nanocrystals. Photoluminescence spectroscopy demonstrated that the photoluminescence intensity of CsPbBr2I and CsPbBr3 varied with impurity doping, indicating an enhancement of semiconductor electronic properties under Ca2+ doping.

Effect of Electronic Properties of Si1-xGex and SiC Semiconductors on the Electrical Behavior of MOS Transistors

In this paper, the electrical performance of Metal-Oxide-Semiconductor MOS transistors in Si1-xGex and SiC technologies have been studied by BSIM3v3 model. In which the output charac- teristic ID=f(VDS), transfer characteristic ID=f(VGS) and ION-IOFF currents of the MOS(Si1-xGex) transis- tors have been investigated and the results so obtained are compared with the MOS(SiC) transistors, using 130 nm technology and OrCAD PSpice software. This study allowed to know the extent to which the electrical behavior of transistors is affected by the most important electronic properties of semiconductors, and the simulation results showed that the above transistors work properly in a regime under a threshold voltage of about 1.2 V. They can be used in low voltage and low power microelectronics by controlling the germanium x fraction and the polytypes of MOS(Si1-xGex) and MOS(SiC) transistors respectively.

Electronic Properties of Group-III Nitride Semiconductors and Device Structures Probed by THz Optical Hall Effect.

Group-III nitrides have transformed solid-state lighting and are strategically positioned to revolutionize high-power and high-frequency electronics. To drive this development forward, a deep understanding of fundamental material properties, such as charge carrier behavior, is essential and can also unveil new and unforeseen applications. This underscores the necessity for novel characterization tools to study group-III nitride materials and devices. The optical Hall effect (OHE) emerges as a contactless method for exploring the transport and electronic properties of semiconductor materials, simultaneously offering insights into their dielectric function. This non-destructive technique employs spectroscopic ellipsometry at long wavelengths in the presence of a magnetic field and provides quantitative information on the charge carrier density, sign, mobility, and effective mass of individual layers in multilayer structures and bulk materials. In this paper, we explore the use of terahertz (THz) OHE to study the charge carrier properties in group-III nitride heterostructures and bulk material. Examples include graded AlGaN channel high-electron-mobility transistor (HEMT) structures for high-linearity devices, highlighting the different grading profiles and their impact on the two-dimensional electron gas (2DEG) properties. Next, we demonstrate the sensitivity of the THz OHE to distinguish the 2DEG anisotropic mobility parameters in N-polar GaN/AlGaN HEMTs and show that this anisotropy is induced by the step-like surface morphology. Finally, we present the temperature-dependent results on the charge carrier properties of 2DEG and bulk electrons in GaN with a focus on the effective mass parameter and review the effective mass parameters reported in the literature. These studies showcase the capabilities of the THz OHE for advancing the understanding and development of group-III materials and devices.

Doping Effects and Relationship between Energy Band Gaps, Impact of Ionization Coefficient and Light Absorption Coefficient in Semiconductors

The doping process is very important in semiconductor technology that is widely used in the production of electronic devices. The effects of doping on the resistivity, mobility and energy band gap of semiconductors are significant and can greatly impact the performance of electronic devices. This thesis aims to investigate the impact of doping on the resistivity, mobility, energy band gap, impact of ionization coefficient, and light absorption coefficient of semiconductors. The study involves an in-depth analysis of the electronic properties of doped semiconductors and their behavior in various conditions. This thesis will provide a comprehensive understanding of the impact of doping on the electronic properties of semiconductors. The energy band gap, impact of ionization coefficient, and Light absorption coefficient were observed in this thesis. In the experimental result, the relation between energy band gap and atomic density, light absorption coefficient and atomic density, impact ionization and atomic density, impact ionization coefficient and Light absorption coefficient, resistivity and mobility has been found.

Increasing Chemical Diversity of B2 N2 Anthracene Derivatives by Introducing Continuous Multiple Boron-Nitrogen Units.

Increasing the chemical diversity of organic semiconductors is essential to develop efficient electronic devices. In particular, the replacement of carbon-carbon (C-C) bonds with isoelectronic boron-nitrogen (B-N) bonds allows precise modulation of the electronic properties of semiconductors without significant structural changes. Although some researchers have reported the preparation of B2 N2 anthracene derivatives with two B-N bonds, no compounds with continuous multiple BN units have been prepared yet. Herein, we report the synthesis and characterization of a B2 N2 anthracene derivative with a BNBN unit formed by converting the BOBN unit at the zigzag edge. Compared to the all-carbon analogue 2-phenylanthracene, BNBN anthracene exhibits significant variations in the C-C bond length and a larger highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap. The experimentally determined bond lengths and electronic properties of BNBN anthracene are confirmed through theoretical calculations. The BOBN anthracene organic light-emitting diode, used as a blue host, exhibits a low driving voltage. The findings of this study may facilitate the development of larger acenes with multiple BN units and potential applications in organic electronics.

Increasing Chemical Diversity of B2N2 Anthracene Derivatives by Introducing Continuous Multiple Boron‐Nitrogen Units

AbstractIncreasing the chemical diversity of organic semiconductors is essential to develop efficient electronic devices. In particular, the replacement of carbon‐carbon (C−C) bonds with isoelectronic boron‐nitrogen (B−N) bonds allows precise modulation of the electronic properties of semiconductors without significant structural changes. Although some researchers have reported the preparation of B2N2 anthracene derivatives with two B−N bonds, no compounds with continuous multiple BN units have been prepared yet. Herein, we report the synthesis and characterization of a B2N2 anthracene derivative with a BNBN unit formed by converting the BOBN unit at the zigzag edge. Compared to the all‐carbon analogue 2‐phenylanthracene, BNBN anthracene exhibits significant variations in the C−C bond length and a larger highest occupied molecular orbital–lowest unoccupied molecular orbital energy gap. The experimentally determined bond lengths and electronic properties of BNBN anthracene are confirmed through theoretical calculations. The BOBN anthracene organic light‐emitting diode, used as a blue host, exhibits a low driving voltage. The findings of this study may facilitate the development of larger acenes with multiple BN units and potential applications in organic electronics.

Surface scattering-dependent electronic transport in ultrathin scandium nitride films

With the constant miniaturization of device technologies, it has become essential to understand and engineer the electronic properties of semiconductors in nanoscale dimensions. Scandium nitride (ScN), an emerging rock salt indirect bandgap semiconductor, has attracted significant interest for its interesting thermoelectric, plasmonic, neuromorphic computing, and Schottky barrier device applications. However, an in-depth understanding of the electronic transport, carrier scattering mechanism, and optical properties in ultrathin ScN films is still missing. Here, we show surface-scattering dominant electronic transport in epitaxial ScN films at nanoscale thicknesses. At the ultrathin dimensions, surface scattering increases significantly due to the large surface-to-volume ratio and growth-induced texturing. As a result, mobility decreases, and resistivity increases drastically with decreasing film thickness. Temperature-dependent electronic transport shows that the mobility of the ultrathin films decreases with increasing temperature due to the ionized-impurity and dislocation scattering. Electronic transport properties are further rationalized with x-ray diffraction and pole-figure analysis that shows that while the ultrathin films maintain their predominant 002 texture, their quality degrades with decreasing thickness. However, no significant changes are observed in the electronic structure of the films, as evidenced by x-ray photoelectron spectroscopy, photoemission measurements, and first-principles density functional theory calculations. Our results elucidate the impact of surface scattering on the ultrathin ScN films and would lead to miniaturized devices with improved efficiencies.

Analysis of plasma-elastic component of time-domain photoacoustic response

The plasma-elastic component of the photoacoustic response in the time-domain of thin semiconductor samples excited by long electromagnetic radiation pulses is analyzed in detail. The plasma-elastic component model assumes that ambipolar diffusion can be approximated by the minority carrier diffusion. The results obtained show that the plasma-elastic component in thin semiconductor samples affects photoacoustic measurements in the time domain, which is important for the photoacoustic determination of semiconductor electronic properties.

Radiation and Emission Phenomena in Combination

Radiation and Emission Phenomena in Combination

Ionic and electronic energy diagrams for hybrid perovskite solar cells.

The development of photoelectrochemical devices based on mixed ionic-electronic conductors requires knowledge of transport, generation and reaction of electronic and ionic charge carriers. Thermodynamic representations can significantly help the understanding of these processes. They should be simple and reflect the necessity of dealing with ions and electrons. In this work, we discuss the extension of energy diagrams commonly used to describe electronic properties of semiconductors to the defect chemical treatment of electronic and ionic charge carriers in mixed conducting materials as introduced in the context of nanoionics. We focus on hybrid perovskites in relation to their use as the active layer material of solar cells. Owing to the presence of at least two ion types, a variety of native ionic disorder processes have to be dealt with in addition to the single fundamental electronic disorder process as well as potential frozen-in defects. Various situations are discussed that show how such generalized level diagrams can be usefully applied and appropriately simplified in the determination of the equilibrium behavior of bulk and interfaces in solar cell devices. This approach can serve as a basis for investigating the behavior of perovskite solar cells, but also other mixed-conducting devices operating under bias.

Defects study in zinc blende ZnS utilizing optimized hybrid functional

Due to its wide band gap and widespread availability in single crystals as well as thin film, zinc sulfide (ZnS) has been applied in many areas. Unfortunately, experimental studies alone are not always sufficient to understand the electronic properties of semiconductors, especially their intrinsic point defects. It is thus necessary to perform theoretical calculations along with the characterization experiments to elucidate their defect characteristics. Density functional theory (DFT) with (semi)local exchange correlation is not often appropriate for describing defects in wide band gap semiconductors, while hybrid functional that do not enforce generalized Koopmans theorem (gKT) are not entirely reliable for predicting the properties of point defects in semiconductors. In this study, we have tuned exact-exchange parameters of hybrid functional to not only reproduce the experimental band gap but also satisfy the gKT for zinc blende (ZB) ZnS. With the new optimized hybrid functional, we study the intrinsic defects in ZB ZnS. Using this optimized hybrid functional we study the intrinsic defects of ZB ZnS. The results show that intrinsic defects have deep charge-transition levels. Among these defects, the zinc vacancy (Znvac) is energetically preferable in a n-type undoped sample either in Zn-rich or S-rich conditions. The calculated emission energy by the combination of an electron from the conduction band minimum and a trapped hole at Znvac2- is 3.17 eV. This calculation is the first theoretical result that explains the origin of the deep-blue emission in ZB ZnS.

C3Al: A tunable bandgap semiconductor with high electron mobility and negative Poisson’s ratio

Two-dimensional materials with suitable band gaps and high carrier mobility are considered to be ideal for fabricating next-generation microelectronics devices. In this paper, the C 3 Al crystal structure, electronic and mechanical properties are systematically investigated based on a first-principles method. We find that C 3 Al is an auxetic semiconductor material with wide band gap and high carrier mobility. Electrons have good transport properties but holes are almost completely scattered in the zigzag direction. C 3 Al is one of the few materials with negative Poisson’s ratio effect. In addition, the electronic properties of C 3 Al can transform from semiconductor to metal by tuning straining and stacking. The bare-edge and H-terminated C 3 Al nanoribbons shows an enriched set of electronic properties of semiconductors, half-semiconductor, bipolar magnetic semiconductors , non-magnetic metals, magnetic metals, and half-metals. These results not only provide a theoretically novel and promising crystal configuration, but also further explore the potential of the material for applications in biosensing, strain sensors, transistors, and various nano-optical devices. • The C 3 Al has excellent performance in terms of structural and thermodynamic stability. • C 3 Al is an auxetic semiconductor material with wide band gap and high carrier mobility. • The electronic properties of C 3 Al can transform from semiconductor to metal by tuning strain and stacking. • The bare-edge and H-terminated C 3 Al nanoribbons show an enriched set of electronic properties.

Atomic-scale characterization of highly doped Si impurities in GaAs using scanning tunneling microscopy

Characterizing the atomic arrangement and distribution of dopant atoms is important for the fundamental understanding of the effects of doping on the electronic properties of semiconductors. Here, we used scanning tunneling microscopy (STM) to image the dopant species in highly Si-doped GaAs. Based on the distinct features in the STM images, we identified the most common Si species, which enabled the accurate evaluation of the local donor and acceptor concentrations and their in-plane variation across different regions. Systematic analysis of the variation of these properties with the doping concentration and the changes after the post-annealing process allowed atomic-scale information about the detailed behaviors of the Si species to be directly extracted. Our findings provided strong insights into the possible roles of each Si species in modifying the macroscopic electronic properties of GaAs.

Efficacy of the Method of Four Coefficients to Determine Charge-Carrier Scattering

The investigation of the electronic properties of semiconductors is inherently challenging due to the ensemble averaging of fundamentals to transport measurements (i.e., resistivity, Hall, and Seebeck coefficient measurements). Here, we investigate the incorporation of a fourth measurement of electronic transport, the Nernst coefficient, into the analysis, termed the method of four-coefficients. This approach yields the Fermi level, effective mass, scattering exponent, and relaxation time. We begin with a review of the underlying mathematics and investigate the mapping between the four-dimensional material property and transport coefficient spaces. We then investigate how the traditional single parabolic band method yields a single, potentially incorrect point on the solution sub-space. This uncertainty can be resolved through Nernst coefficient measurements and we map the span of the ensuing sub-space. We conclude with an investigation of how sensitive the analysis of transport coefficients is to experimental error for different sample types.

Surface Photovoltage Spectroscopy over Wide Time Domains for Semiconductors with Ultrawide Bandgap: Example of Gallium Oxide

A nonconventional approach is proposed for the measurement of surface photovoltage (SPV) signals over very wide ranges in photon energy and time. Regimes for AC, DC, and combined AC–DC measurements are defined and applied for the characterization of a β‐Ga2O3 crystal by transient and modulated SPV spectroscopy, spectroscopy in the mode of a Kelvin probe and single‐pulse SPV transients from 10 ns to 1000 s with the same electrode. Numerous electronic transitions are distinguished in β‐Ga2O3 depending on the measurement regime, the time response and the history of measurement. An accumulation of negative charge at the surface of β‐Ga2O3 is observed at long times independent whether the SPV signals are positive or negative before. The nonconventional approach of measuring SPV signals opens new opportunities for investigating electronic properties of semiconductors with ultrawide bandgaps and any other photoactive materials.

Observation of local vibrational modes in N-doped 6H-SiC

Doping plays a vital role in tuning the carrier concentration and also influences various electronic properties in semiconductors. In addition to tuning the electronic properties of semiconductors, impurities also affect vibrational properties. We report the local vibrational modes (LVMs) in N-doped n-type 6H-SiC. New phonon modes are observed in the low-temperature range. Unlike lattice phonons, LVMs are localized in both the real space and frequency domains and give rise to a distinct signature in the Raman spectra. In the present study, LVMs in N-doped 6H-SiC are identified as N atom vibrations with the help of lattice dynamical calculations of the phonon density of states using generalized gradient approximation. Moreover, the stability of the SiC is investigated for a wide temperature range signifying its application in micro-electro-mechanical systems technology. Therefore, the present study provides insight for understanding both lattice phonons and the impurity-induced vibrational modes using Raman spectroscopic analysis in corroboration with the calculation of phonon density of states.

Structures, bonding, and electronic properties of metal thiocyanates

Metal thiocyanates, such as copper(I) thiocyanate (CuSCN) and tin(II) thiocyanate [Sn(SCN)2], are emerging as novel semiconductors for electronic applications, and while other thiocyanate coordination polymers are known, their electronic structures and properties have not been investigated. In this work, we employed density functional theory (DFT) and crystal orbital Hamilton population (COHP) to analyze the electronic structures and bonding character of 18 structures of 15 metal thiocyanate compounds as well as a main group thiocyanate, selenium thiocyanate [Se(SCN)2]. Interestingly, the ionic thiocyanates (groups 1 and 2) display band dispersions despite their valence and conduction bands (VBs and CBs) being derived mostly from the thiocyanate ligand. Thiocyanates of group 11 show the strongest contributions from the metals with their d electrons strongly dominating the top of the VBs. In contrast, metals from group 12 contribute their s electrons to the bottom CBs. Metals of groups 13 and 14 have lone pair electrons in the s orbitals, which are featured at the top of their VBs, while the metal p states contribute to the CBs. The bonding character and orbital contributions can be explained based on the trend in the electron binding energies of the coordinated atoms. The versatility of adjusting the orbital contribution by changing the metals can be used for tuning the electronic properties of semiconductors based on thiocyanate compounds.

Quantum Sensor for Nanoscale Defect Characterization

The optical and electronic properties of semiconductors are strongly affected by structural and stoichiometric defects. The precise incorporation of dopants and the control of impurities are essentially what makes semiconductors useful materials for a broad range of devices. The standard defect and impurity characterization methods are sensitive only on a macroscopic scale, like the most widely used method of deep-level transient spectroscopy (DLTS). We perform time-resolved measurements of the resonance fluorescence of a single self-assembled $(\mathrm{In},\mathrm{Ga})$$\mathrm{As}$ quantum dot (QD) at low temperatures ($4.2\phantom{\rule{0.2em}{0ex}}\mathrm{K}$). By pulsing the applied gate voltage, we are able to selectively occupy and unoccupy individual defects in the vicinity of the dot. We address the exciton transition of the QD with a tunable diode laser. Our time-resolved measurements exhibit a shift of the resonance energy of the optical transition. We attribute this to a change of the electric field in the dot's vicinity, caused by electrons tunneling from a reservoir to the defect sites. Furthermore, we are able to characterize the defects concerning their position and activation energy by modeling our experimental data. Our results thus demonstrate how a quantum dot can be used as a quantum sensor to characterize the position and activation energy of individual shallow defects on the nanoscale.

Significance of nanostructure morphologies in photoelectrochemical water splitting cells: A brief review

The main component in photoelectrochemical (PEC) water splitting technology is the semiconductor, which its electronic structure has an essential effect on the final performance of the cell. Morphology plays a significant role in the electronic properties of semiconductors. The relationship between the electron and optical properties of nanostructures and their surface morphology is a subject that is less addressed in scientific papers. This review attempts to detail the impact of morphology on nanostructures' properties, such as light absorption and charge carrier transport. Creating a direct path for electron transport, reducing charge recombination, and increasing light scattering are some of the things that are directly related to the surface morphology of nanostructures. The present review aims to provide general information about synthesized nanostructures and their advantages and disadvantages to help readers create new ideas and innovate in this field.