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About 10,000 papers for “Heterojunction”

heterojunction

2024

Citation: 'heterojunction' in the IUPAC Compendium of Chemical Terminology, 5th ed.; International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.08825 • License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International for individual terms. Requests for commercial usage of the compendium should be directed to IUPAC.

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Heterojunction

Jiřı́ Vohlı́dal, Carlos F. O. Graeff, Roger C. Hiorns et al. · IUPAC Standards Online · 2023

These recommendations are specifically for polymers and polymer systems showing a significant response to an electromagnetic field or one of its components (electric field or magnetic field), i.e., for electromagnetic-field-responsive polymer materials. The structures, processes, phenomena and quantities relating to this interdisciplinary field of materials science and technology are herein defined. Definitions are unambiguously explained and harmonized for wide acceptance by the chemistry, physics, polymer and materials science communities. A survey of typical electromagnetic-field-responsive polymers is included.

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Heterojunction devices

H. Kroemer · 1992

An historial reriew of heterojunction device technology is presented.

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Heterojunction Photocatalysts

Jingxiang Low, Jiaguo Yu, Mietek Jaroniec et al. · Advanced Materials · 2017

Semiconductor-based photocatalysis attracts wide attention because of its ability to directly utilize solar energy for production of solar fuels, such as hydrogen and hydrocarbon fuels and for degradation of various pollutants. However, the efficiency of photocatalytic reactions remains low due to the fast electron-hole recombination and low light utilization. Therefore, enormous efforts have been undertaken to solve these problems. Particularly, properly engineered heterojunction photocatalysts are shown to be able to possess higher photocatalytic activity because of spatial separation of photogenerated electron-hole pairs. Here, the basic principles of various heterojunction photocatalysts are systematically discussed. Recent efforts toward the development of heterojunction photocatalysts for various photocatalytic applications are also presented and appraised. Finally, a brief summary and perspectives on the challenges and future directions in the area of heterojunction photocatalysts are also provided.

Cited by 4,592

Heterojunction Transistors.

J.R. East · Deep Blue (University of Michigan) · 1986

The objective of this investigation is to study the properties of GaAs-based heterojunction transistors in order to better underst and their high-frequency performance. The high-frequency limitations of high-mobility materials are studied by comparing the switching performance of diodes and transistors based on two transport models: a conventional drift-diffusion transport model and a more accurate energy-momentum balance transport model. The drift-diffusion model predicts high-frequency performance limitations because of velocity saturation and hot electron effects. The energy-momentum model predicts poorer high-frequency performance based on velocity overshoot and cool electron effects. It also predicts an underdamped electron velocity due to the inductive nature of the electron velocity. The properties of heterojunction interfaces are studied by comparing three interface models: the Boltzmann model, the Fermi-Dirac model and a model based on quantum statistics. The choice of model is a tradeoff between accuracy and cost. Over the range of temperatures and interface conditions studied, the Fermi-Dirac model predicts interface conditions close to the more accurate quantum-based model using approximately the same amount of computer time as the simple Boltzmann model. The Fermi-Dirac interface model is used as a basis for a two-dimensional model for a high electron mobility transistor structure. The structure is studied over a range of bias, doping and Al fraction conditions in order to better underst and the device operation. The device operation is found to be closer to bipolar transistor operation than conventional field-effect transistor operation. The two-dimensional model is also used to study the properties of ballistic injection structures and ballistic transistors. A simple Monte Carlo model is used to study ballistic injection. The results show that very high velocities can be obtained by ballistic injection, but that the effects occur over relatively short distances. This limits the performance of ballistic transistors.

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HETEROJUNCTION LASERS

Sayfutdinova Sevara Erkinjon qizi, Ermatov Shukrulla Abdulfayzovich · Zenodo (CERN European Organization for Nuclear Research) · 2023

The main parameters of a heterojunction laser diode, such as the emission frequency spectrum (optical modes), threshold current, output radiation power, and operating efficiency, are considered. A simplified formula for the radiation intensity of a heterostructure laser is obtained. It is shown that, due to reflection from the ends, the light repeatedly passes through the active region and is predominantly amplified by stimulated emission. A standing wave is established inside the laser diode with an integer number of half-waves between the end surfaces.

Cited by 0Open access

Heterojunction FETs

Pouya Valizadeh · 2016

Heterojunction field effect transistors (HFETs) are FETs for which the channel is formed in the vicinity of hetero-interface(s) of two (or three) semiconductors of different values of both bandgap and electron affinity. This chapter first discusses challenges and rewards of heteroepitaxy among a few well-known semiconductor families. HFETs have extended an easier path to the realization of very high-speed switches and very high-gain/low-noise transistors suitable for microwave and millimeter-wave applications. The role of quantum phenomena in the operation of these heterostructure-based devices is more pivotal. The chapter presents a brief review of quantum phenomena in semiconductor heterostructures. It also looks into the evolution of energy subbands within the heterostructure quantum wells. The chapter then presents the operation principles of the nonpolar modulation-doped HFETs. It finally deals with polarization doping for the specific example of Wurtzite III-Nitride heterostructure.

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Heterojunction devices

- · Institutional Repository of Xi'an Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (Xian Institute of Optics and Precision Mechanics) · 1978

1499561 Semi-conductor devices UNIVERSITY OF CONNECTICUT 16 Jan 1975 [18 Jan 1974] 1903/75 Heading H1K Heterojunction devices.-A semi-conductor device including a heterojunction comprises two crystallographically compatible semi-conductor materials A, B, 72, 71, Fig. 4, having different energy bandgaps such that the bandgap of material A is less than that of material B, and mirror-smooth surfaces, and being joined together at a junction 70 to form a single crystal, the junction 70 having a width over which transition from atoms of material A to atoms of materials B occurs of less than about 2000 , there being substantially no crossdiffusion of dopants or autodoping of the materials across the junction 70, and the material B having an average resistivity less than 5À103 ohm cm. in the direction parallel to the plane of the junction, whereby, in a heterodiode containing the heterojunction, the minority carriers in the material A have a long lifetime and at least one of the following characteristics: (a) sharp current-voltage characteristics, (b) abrupt avalanche breakdown, (c) low junction capacitance. Manufacture.-The heterojunction 70 may be incorporated in a number of stated devices and is formed by epitaxial deposition in an elongate reaction zone 10, Fig. 2, under anhydrous and oxygen-free conditions and in the absence of hydrogen iodide-promoting substances. The zone 10 contains iodine 16 in a source zone 14, a substrate of the material B on a support 18 in a seed zone 20, and germanium 22 in a source zone 21 therebetween. A carrier gas containing hydrogen, an inert gas and a dopant are introduced into the reaction zone 10 and the zones 14, 21, 20 are heated to specified low, high and medium temperatures respectively. Germanium diiodide is produced in the reaction zone 10 and a disproportionation reaction occurs in the seed zone 20 where germanium is epitaxially deposited on the substrate. The pairs of semi-conductor materials include Ge/GaAs, Ge/ZnSe, GaAs/ZnSe, AlAs/GaAs, GaSb/InAs, ZnTe/GaSb, Ge 0À9 Si 0À1 / Ge, CdTe/InSb.

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HETEROJUNCTION DEVICES.

Anderson,R. L., Zeidenbergs,G., Yawata,S. et al. · Defense Technical Information Center (DTIC) · 1965

The opto-electric characteristics of abrupt Ge-GaAs heterojunctions have been investigated to determine if such devices are efficient photon detectors. Because of a notch in the band edge at the interface the quantum efficiency is low. Further, such a device as the collector in an optical transistor is concluded to be impractical. A method of determining the minority carrier lifetime in the Ge adjacent to the GaAs, from the photocurrent spectrum, is developed. Near the band gap of Ge, the photocurrent spectrum exhibits changes in slope attributable to the onset of phonon assisted absorption. An efficient photodetector is described which utilizes a Ge-Si n-n heterojunction. A qualitative theory for this is developed. Photo-excited holes are trapped in the notch in the valence band which in turn modulates the diode current. Attempts to fabricate a wide band gap transistor have been unsuccessful. It was determined that a poor injection efficiency resulting from a predominance of recombination current in the GaAs is at fault. An apparatus for probing semiconductor devices is described. The thermoelectric and photovoltaic methods are used. (Author)

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