Transport In Heterostructures Research Articles

On Analysis of Mass Transport to Formulate Conditions for Increasing Integration Rate of Elements Framework Current Comparator in Sensor Applications. An Approach to Optimize of Technological Process

Framework the paper we consider an analytical approach to analyze mass and heat transport in heterostructures during manufacturing of integrated circuits with account nonlinearity of processes. The approach gives a possibility to analyze mass and heat transport in multilayer structures without crosslinking of solutions on interfaces between layers. The approach also gives a possibility to take into account spatial and temporal variation of parameters of considered processes. Based on this approach we analyzed manufacturing a current comparator for sensor applications to increase density of elements.

Nickel Oxide–Based Heterostructures with Large Band Offsets

The authors present research on the electronic transport in heterostructures based on p‐type nickel oxide (NiO) with the n‐type oxide semiconductors zinc oxide (ZnO) and cadmium oxide (CdO). NiO is a desirable candidate for application in (opto)electronic devices. Because of its small electron affinity, heterojunctions with most n‐type oxide semiconductors exhibit conduction and valence band offsets at the heterointerface in excess of 1 eV. ZnO/NiO junctions exhibit a so‐called type‐II band alignment, making interfacial electron–hole recombination the only process enabling vertical current flow through the structure. These heterojunctions are nevertheless shown to be of practical use in optoelectronic devices, as exemplified here by UV‐converting transparent solar cells. These devices, although exhibiting high conversion efficiencies, suffer from two light‐activated recombination channels connected to the type‐II interface, one of which the authors analyze in more detail here. Furthermore, CdO/NiO contacts are studied—a heterostructure with even larger band offsets, achieving a type‐III band alignment which theoretically enables the development of a 2D electronic system consisting of topologically protected states. The authors present experiments demonstrating that CdO/NiO heterostructures indeed hosts a conductive layer absent in both materials when studied separately.

Formation of the Magnetic Order in Three-Dimensional Topological Insulators for the Quantum Anomalous Hall Effect (Scientific Summary)

The topical problem of realization of the proper transverse conductivity in magnetic heterostructures based on topological insulators has been discussed. Our recent theoretical studies developing a universal approach to analytically simulate the quantum anomalous Hall effect at various ways for introducing a magnetic order into a topological insulator film have been briefly reviewed. Our model involves a consistent description of electronic states of the system, which determine the quantum anomalous Hall effect, with the reduction of the dimension from three-dimensional bulk through two-dimensional interface to one-dimensional edge. This makes it possible to emphasize the particular role of physical boundaries such as interfaces and side faces for spin-dependent transport in heterostructures. A number of new results recently obtained within the proposed approach have been reported. The data of recent experiments with new magnetic materials and structures have been discussed in terms of our theoretical results.

Spintronics – A mini review

Abstract Over the last decade, the construction and analysis of spintronic devices have been explored. This mini-review focuses on the basic spintronic phenomena such as giant magnetoresistance, tunnel magnetoresistance, spin transfer torque, spin Hall effect, spin Seebeck effect and BGKC (Bruno – Gnanasekar – Karunakaran – Chandramohan) observation. The mechanism of spin-orbit interaction is theoretically discussed. The in-plane wave vector, magnetic field, bias voltage and the delta potential are influenced on spin-polarized transport in heterostructures. The comparison between the role of Dresselhaus and Rashba spin-orbit interaction in the heterostructure is investigated. The principle of spintronic devices (sensors, magnetic random access memory, unipolar spin diode, spin photodiode, spin LED, spin solar cell, spin FET) and spintronic instruments (spin SEM, spin STM) are also explained.

Towards high-temperature coherence-enhanced transport in heterostructures of a few atomic layers

The possibility to exploit quantum coherence to strongly enhance the efficiency of charge transport in solid state devices working at ambient conditions would pave the way to disruptive technological applications. In this work, we tackle the problem of the quantum transport of photogenerated electronic excitations subject to dephasing and on-site Coulomb interactions. We show that the transport to a continuum of states representing metallic collectors can be optimized by exploiting the "superradiance" phenomena. We demonstrate that this is a coherent effect which is robust against dephasing and electron-electron interactions in a parameters range that is compatible with actual implementation in few monolayers transition-metal-oxide (TMO) heterostructures.

On Optimization of Manufacturing of Bipolar Heterotransistors Framework Circuit of a High-voltage Element or to Increase Their Integration Rate: On Influence Mismatch-induced Stress

In this paper, we introduce an approach to decrease dimensions of bipolar heterotransistors framework a circuit of a voltage divider biasing common emitter amplifier. Framework of the approach, we consider manufacturing of the divider in heterostructure with specific configuration. Several specific areas of the heterostructure should be doped by diffusion or by ion implantation. After this doping, dopant and/or radiation defects should be annealed by using optimized scheme. We also consider an approach to decrease value of mismatch-induced stress in the considered heterostructure. To make prognosis of technological process and obtain recommendations to optimize the process, we introduce an analytical approach to analyze mass and heat transport in heterostructures with account mismatch-induced stress.

Electronic Transport and Thermopower in 2D and 3D Heterostructures—A Theory Perspective

AbstractThe impact of interfaces and heterojuctions on the electronic and thermoelectric transport properties of materials is discussed herein. Recent progress in understanding electronic transport in heterostructures of 2D materials ranging from graphene to transition metal dichalcogenides, their homojunctions (grain boundaries), lateral heterojunctions (such as graphene/MoS2 lateral interfaces), and vertical van der Waals heterostructures is reviewed. Work on thermopower in 2D heterojunctions, as well as their applications in creating devices such as resonant tunneling diodes (RTDs), is also discussed. Last, the focus turns to work in 3D heterostructures. While transport in 3D heterostructures has been researched for several decades, here recent progress in theory and simulation of quantum effects on transport via the Wigner and non‐equilibrium Green's functions approaches is reviewed. These simulation techniques have been successfully applied toward understanding the impact of heterojunctions on transport properties and thermopower, which finds applications in energy harvesting, and electron resonant tunneling, with applications in RTDs. In conclusion, tremendous progress has been made in both simulation and experiments toward the goal of understanding transport in heterostructures and this progress will soon be parlayed into improved energy converters and quantum nanoelectronic devices.

On approach to optimize manufacturing of field-effect hetero transistors frame work a HERIC-inverter to increase their integration rate. On influence mismatch-induced stress


 
 
 In this paper we introduce an approach to increase density of field-effect transistors framework a circuit of HERIC-inverter with photovoltaic (PV) systems. Framework the approach we consider manufacturing the inverter in heterostructure with specific configuration. Several required areas of the hetero structure should be doped by diffusion or ion implantation. After that dopant and radiation defects should by annealed framework optimized scheme. We also consider an approach to decrease value of mismatch-induced stress in the considered heterostructure. We introduce an analytical approach to analyze mass and heat transport in heterostructures during manufacturing of integrated circuits with account mismatch-induced stress.
 
 

Making graphene useful for spintronics

Spintronics Thanks to graphene's weak spin-orbit coupling, spin currents flow through it unimpeded. However, this also means that the spin currents are hard to manipulate—a drawback for using graphene in spintronics. Two groups now show that this needn't be the case. Leutenantsmeyer et al. and Xu et al. studied spin transport in heterostructures of bilayer graphene with hexagonal boron nitride. In the presence of an electric field, the spin lifetimes in the directions parallel to the heterostructural layers and perpendicular to them were markedly different. The long and anisotropic lifetimes may lead to useful spintronics applications. Phys. Rev. Lett. 121 , 127702, 127703 (2018).

Impact of interface types on spin transport in heterostructures of graphene/hexagonal boron-nitride nanoribbons

Abstract Using density functional theory in combination with non-equilibrium Green's functions, we investigate the spin transport in two heterostructures of graphene and hexagonal boron-nitride (h-BN) nanoribbons with C-B and C-N interfaces, respectively. Significant spin-filtering effect (over 80%) is observed in both C-B and C-N devices with bias ranging from 0 V to 0.3 V. Interestingly, the spin polarizations are opposite in these two devices, and prominent negative differential resistance (NDR) for both spin-up and spin-down currents is observed only in the C-N device. These findings provide insight into how the spin-transport properties of graphene/h-BN nanoribbons can be impacted by different types of interfaces of the heterostructures.

Green's function formalism for spin transport in metal-insulator-metal heterostructures

We develop a Green's function formalism for spin transport through heterostructures that contain metallic leads and insulating ferromagnets. While this formalism in principle allows for the inclusion of various magnonic interactions, we focus on Gilbert damping. As an application, we consider ballistic spin transport by exchange magnons in a metal-insulator-metal heterostructure with and without disorder. For the former case, we show that the interplay between disorder and Gilbert damping leads to spin current fluctuations. For the case without disorder, we obtain the dependence of the transmitted spin current on the thickness of the ferromagnet. Moreover, we show that the results of the Green's function formalism agree in the clean and continuum limit with those obtained from the linearized stochastic Landau-Lifshitz-Gilbert equation. The developed Green's function formalism is a natural starting point for numerical studies of magnon transport in heterostructures that contain normal metals and magnetic insulators.

33rd International Conference on the Physics of Semiconductors

Preface to the Proceedings of the 33rd International Conference on the Physics of Semiconductors, Beijing, 2016Shaoyun Huang1, Yingjie Xing1, Yang Ji2, Dapeng Yu3, and Hongqi Xu11Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China2SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China3State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, ChinaFrom July 31st to August 5th, 2016, the 33rd International Conference on the Physics of Semiconductors (ICPS 2016) was held in Beijing, China, with a great success. The International Conference on the Physics of Semiconductors began in the 1950’s and is a premier biennial meeting for reporting all aspects of semiconductor physics including electronic, structural, optical, magnetic and transport properties. Reflecting the state of the art developments in semiconductor physics, ICPS 2016 served as an international forum for scholars, researchers, and specialists across the globe to discuss future research directions and technological advancements. The main topics of ICPS 2016 included:• Material growth, structural properties and characterization, phonons• Wide-bandgap semiconductors• Narrow-bandgap semiconductors• Carbon: nanotubes and graphene• 2D Materials beyond graphene• Organic semiconductors• Topological states of matter, topological Insulators and Weyl semimetals• Transport in heterostructures• Quantum Hall effects• Spintronics and spin phenomena• Electron devices and applications• Optical properties, optoelectronics, solar cells• Quantum optics, nanophotonics• Quantum information• Other topics in semiconductor physics and devices• Special topic: Majorana fermions in solid state

Resonant tunneling and intrinsic bistability in twisted graphene structures

We predict that vertical transport in heterostructures formed by twisted graphene layers can exhibit a unique bistability mechanism. Intrinsically bistable $I$-$V$ characteristics arise from resonant tunneling and interlayer charge coupling, enabling multiple stable states in the sequential tunneling regime. We consider a simple trilayer architecture, with the outer layers acting as the source and drain and the middle layer floating. Under bias, the middle layer can be either resonant or non-resonant with the source and drain layers. The bistability is controlled by geometric device parameters easily tunable in experiments. The nanoscale architecture can enable uniquely fast switching times.

Negative differential resistance in boron nitride graphene heterostructures: physical mechanisms and size scaling analysis.

Hexagonal boron nitride (hBN) is drawing increasing attention as an insulator and substrate material to develop next generation graphene-based electronic devices. In this paper, we investigate the quantum transport in heterostructures consisting of a few atomic layers thick hBN film sandwiched between graphene nanoribbon electrodes. We show a gate-controllable vertical transistor exhibiting strong negative differential resistance (NDR) effect with multiple resonant peaks, which stay pronounced for various device dimensions. We find two distinct mechanisms that are responsible for NDR, depending on the gate and applied biases, in the same device. The origin of first mechanism is a Fabry-Pérot like interference and that of the second mechanism is an in-plane wave vector matching when the Dirac points of the electrodes align. The hBN layers can induce an asymmetry in the current-voltage characteristics which can be further modulated by an applied bias. We find that the electron-phonon scattering suppresses the first mechanism whereas the second mechanism remains relatively unaffected. We also show that the NDR features are tunable by varying device dimensions. The NDR feature with multiple resonant peaks, combined with ultrafast tunneling speed provides prospect for the graphene-hBN-graphene heterostructure in the high-performance electronics.

Electronic transport in heterostructures of chemical vapor deposited graphene and hexagonal boron nitride.

CVD graphene devices on stacked CVD hexagonal boron nitride (hBN) are demonstrated using a novel low-contamination transfer method, and their electrical performance is systematically compared to devices on SiO(2). An order of magnitude improvement in mobility, sheet resistivity, current density, and sustained power is reported when the oxide substrate is covered with five-layer CVD hBN.

Influence of microwave plasma microprocessing on the electronic properties of the (100)Si surface

The feasibility of controlling the electronic properties of the semiconductor surface by varying conditions for its processing is considered. The study of electron transverse transport in heterostructures based on a (100)Si single crystal and a tunnel-thin film of hydrogenized amorphous silicon carbide shows that the form of the I–V characteristic of such structures depends on the density of dangling bonds on the surface. They arise when silicon single crystals of a given orientation are subjected to microprocessing by a highly ionized microwave plasma in different plasma-forming media to obtain an atomically clean surface.

Preface to Special Topic: Selected Contributions to the 31st International Conference on the Physics of Semiconductors, Zurich, 2012

(Received 26 February 2013; accepted 6 March 2013; published online 29 March 2013)[http://dx.doi.org/10.1063/1.4795810]It is our great pleasure to present in this issue of theJournal of Applied Physics selected contributions to the 31stInternational Conference on the Physics of Semiconductors(ICPS-31), which took place in Zurich, Switzerland, fromJuly 29 to August 3rd, 2012. The contributions comprise theplenary talk by Professor Hideo Ohno on “Bridging semicon-ductor and magnetism” and ten invited talks by differentauthors. The articles in this collection have undergone thesame peer-review process as regular journal articles.The International Conference on the Physics ofSemiconductors has a long history and covers all the impor-tant subfields of this research area. The thirteen specifictopics presented at the Zurich conference in 2012 were1. Material Structure,2. Wide Bandgap Semiconductors,3. Narrow-gap Semiconductors,4. Carbon: Nanotubes and Graphene,5. Organic Semiconductors,6. Topological Insulators,7. Transport in Heterostructures,8. Quantum Hall Effects,9. Spintronics and Spin Phenomena,10. Electron Devices and Applications,11. Optical Properties of Heterostructures,12. Quantum Optics and Nanophotonics,13. Quantum Information.Since the first conference took place in Reading,England, in 1950, the field of Semiconductor Physics hascontinued to present exciting new and important results forphysicists and engineers. At ICPS-31, highlights also cov-ered with plenary talks were the progress in quantum infor-mation processing with single spins and spintronics, theexperimental and theoretical investigation of Majorana fer-mions, the physics of graphene, exciton-polariton conden-sates, and solid-state cavity QED with a quantum dotcoupled to a photonic crystal.The organizers of ICPS31 are particularly grateful forthe continued partnership with the American Institute ofPhysics that allows us to publish plenary and invited papersin the Journal of Applied Physics, thus making the valuablecontributions of the most committed invited and plenaryspeakers available to a broad audience in applied physicsand related fields. We wish to thank the authors who took theextra effort to condense their excellent talks into the pre-sented journal articles. We hope that the readers will find theresults interesting and scientifically stimulating.

Magnetoresistance enhanced by inelastic cotunneling in a ferromagnetic MnAs nanoparticle sandwiched by nonmagnetic electrodes

We investigated electron transport and magnetoresistance (MR) of a nanoparticle system by measuring the vertical transport in heterostructures containing ferromagnetic MnAs nanoparticles and nonmagnetic electrodes. The origin of MR is attributed to the tunneling anisotropic MR (TAMR) of a MnAs nanoparticle because the path of electrons includes only a single ferromagnetic material, and MR shows magnetic-field direction dependence. From the very similar temperature dependence of the intensity of inelastic cotunneling and MR, it is strongly suggested that MR is enhanced by spin-dependent inelastic cotunneling. The temperature dependence of MR is explained by the magnetic energy barrier ETAMR induced by TAMR, and ETAMR is estimated to be ∼0.26 meV.

Main features of photostimulated ion transport in heterojunctions based on mixed ion-electron (hole) conductors and the model of a thin-film ion accelerator

The main features of photostimulated ion transport in heterostructures based on mixed ion-electron (hole) conductors are considered. It is shown that, using correctly chosen physical factors and a heterostructure of special design, one can implement efficient ion acceleration and thus develop a thin-film ion accelerator.

Independent-Band Tight-Binding Parameters for Fe–MgO–Fe Magnetic Heterostructures

We present a computationally efficient and transferable independent-band tight-binding model (IBTB) for spin-polarized transport in heterostructures with an effort to capture the band structure effects. As an example, we apply it to study the transport through Fe-MgO-Fe(100) magnetic tunnel junction devices. We propose a novel approach to extract suitable tight-binding parameters for a material by using the energy resolved transmission as the benchmark, which inherently has the band structure effects over the 2-D transverse Brillouin zone. The IBTB parameters for various symmetry bands for bcc Fe(1 0 0) are first proposed which are complemented with the transferable tight-binding parameters for the MgO tunnel barrier for the Δ1-like and Δ5-like bands. The nonequilibrium Green's function formalism is then used to calculate the transport features like J-V characteristics, voltage dependence, and the barrier width dependence of the tunnel magnetoresistance ratio are captured quantitatively, and the trends match well with the ones observed in ab initio methods.