Functional Dependences of the Maximum Energy Density of the Spectral Component of Stimulated Picosecond Emission by GaAs upon Gain Saturation. The Residual Characteristic Emission Relaxation Time

Semiconductors - During high-power optical picosecond pumping of the GaAs layer of an AlxGa1 – xAs–GaAs–AlxGa1 – xAs heterostructure, stimulated...     

Structural and Optical Properties of Wurtzite AlGaAs Nanowires Grown by MBE on Si(111) Substrate

Semiconductors - We present the results of photoluminescence measurements of AlxGa1 – xAs nanowires, together with the transmission electron microscopy structural analysis....     

Electron-Population Bragg Grating Induced in an AlxGa1 –xAs–GaAs–AlxGa1 –xAs Heterostructure by Intrinsic Stimulated Picosecond Emission

Semiconductors - It is shown that modulation of the spectrum of stimulated picosecond emission generated in an AlxGa1 – xAs–GaAs–AlxGa1 – xAs waveguide heterostructure upon...     

AlGaAs湿法氧化特性实验研究

研究了AlxGa1-xAs／GaAs材料中高Al组份的AlxGa1-xAs层在400-500℃与水汽发生氧化反应的氧化特性。许多影响因素,如待氧化层厚度、组分、氧化温度、气体流量都不同程度影响氧化速率,影响到氧化物限制工艺的整体质量。实验得到AlxGa1-xAs中x值、厚度、氧化温度等因素与氧化速率有关,并发现气流量对AlxGa1-xAs层的氧化过程有重要的影响,实验测定了气流量与AlxGa1-xAs层氧化速率的关系。     

Growth conditions to achieve mobility enhancement in AlxGa1?xAs-GaAs heterojunctions by m.b.e.

Modulation doped Al0.25Ga0.75As-GaAs heterojunctions have been prepared by molecular beam epitaxy (m.b.e.). Al0.25Ga0.75As layers were doped with Si to a level of ~ 3 × 1017 cm?3, whereas the GaAs layers were either unintentionally doped, doped lightly n-type with Sn, or doped lightly p-type with Be. Heterojunction structures having single and multiple periods have shown enhanced mobility only with the AlxGa1?xAs layer at the surface and the GaAs layer underlying. These results represent the first report that electrons spill over only into the underlying GaAs layer from the top AlxGa1?xAs layer.     

Excitonic Effects and Impurity–Defect Emission in GaAs/AlGaAs Structures Used for the Production of Mid-IR Photodetectors

Semiconductors - A series of undoped GaAs/AlxGa1 –xAs multiple quantum well heterostructures, whose doped analogs are used for the production of photodetectors operating in the spectral range...     

Electron transport through the MOCVD grown GaAs/AlGaAs/GaAs heterojunction barrier

We investigated the current/voltage characteristics of n+GaAs/undoped AlxGa1?xAs (200 A)/n+GaAs heterostructures grown by the metalorganic chemical vapour deposition (MOCVD) method between 77 K and 300 K. Both the voltage dependence and the temperature dependence of the current were in good agreement over a wide current range with the calculated results of the tunnelling and thermionic emission current.     

Temporal resolution of an AlxGa1?xAs/GaAs bias-free photodetector

We report on the measurement of the temporal resolution limit of a recently reported AlxGa1?xAs/GaAs bias-free photodetector. When tested by dual synchronously pumped dye laser pulses with a repetition rate of 80 MHz and an attenuated energy per pulse of 30 pJ, the detector shows a resolution limit of ? 65 ps.     

Capacitance Spectroscopy of Heteroepitaxial AlGaAs/GaAs p–i–n Structures

Semiconductors - The temperature dependences of the capacitance-voltage (C–V) characteristics and deep-level spectra of a graded high-voltage AlxGa1 – xAs p0–i–n0 junction...     

Hot-electron injection by graded AlxGa1?xAs

Triangular barriers of AlxGa1?xAs are used as hot-electron injectors. The AlxGa1?xAs, is linearly graded from x=0 to 0.2 or 0.3 over distances of order 500 ? to provide barriers in the range 200 to 300 meV. In the present application the barrier forms the injector of a hot-electron spectrometer.     

Transport properties in GaAs-AlxGa1?xAs heterostructures and MESFET application

Mobilities of undoped GaAs-n-doped AlxGa1?xAs heterostructures are shown to present a maximum as a function of the thickness of the undoped AlxGa1?xAs spacer layer. This maximum increases as the temperature decreases. The transition temperature above which phonon scattering is dominant decreases as d increases. Heterostructure FETs working at 11 GHz give an 8 dB gain.     

V-DH laser: a laser with a V-shaped active region grown by metalorganic c.v.d.

A single mode c.w. AlxGa1?xAs/GaAs laser was made by metalorganic c.v.d. A double heterostructure with a V-shaped active region and a junction stripe geometry was grown on a groove-etched substrate. The minimum c.w. threshold current and the maximum differential quantum efficiency obtained were 15 mA and 65% (250 ?m length cavity). The laser's beam shape was nearly circular, with an aspect ratio from 1.3 to 1.4.     

Transformation of N-Polar Inversion Domains from AlN Buffer Layers during the Growth of AlGaN Layers

Semiconductors - The structural properties and crystal quality of AlxGa1 ? xN/AlN/Al2O3 heterostructures grown by ammonia-assisted molecular-beam epitaxy with a high silicon...     

1.5 GHz operation of an AlxGa1?xAs/GaAs modulation-doped photoconductive detector

We demonstrate a planar AlxGa1?xAs/GaAs modulation-doped photoconductive detector operating at frequencies up to 1.5 GHz. This detector exhibits a peak responsivity of 2 A/W at these operating conditions, which corresponds to a gain of 3. We found that the peak responsivity increased with reduced pulse repetition rates, reaching 5 A/W at 1 MHz. We also measured the noise power at 800 MHz. This investigation suggests that the detector can be useful for shortwavelength (? ? 0.82 ?m) giga-bit-rate integrated photoreceiver applications.     

Effects of Doping of Bragg Reflector Layers on the Electrical Characteristics of InGaAs/GaAs Metamorphic Photovoltaic Converters

Semiconductors - The current–voltage characteristics of InxGa1 –xAs/GaAs metamorphic photovoltaic converters with built-in n-InGaAs/InAlAs Bragg reflectors are studied at an indium...     

Special features of electron scattering at AlxGa1−x As/AlAs(001) interfaces

Semiconductors - The effect of total reflection of an electron wave from an interface was investigated for AlxGa1−xAs/AlAs structures. Analysis was performed on the basis of calculations by...     

High mobility GaAs-AlxGa1?xAs single period modulation-doped heterojunctions

Single period modulation-doped structures composed of an AlxGa1?xAs layer, part of which is doped with Si, on top of an undoped GaAs layer have been grown by molecular beam epitaxy. The films were characterised using Hall effect measurements carried out at temperatures between 10 and 300 K. With 50?75 ? thick undoped (Al, Ga)As layers near the interface, mobilities in excess of 115000 cm2/Vs at 10 K and 7450 cm2/Vs at 300 K have been achieved for an average doping concentration of ?5×1016 cm?3. These are some of the highest mobilities as yet obtained from modulation-doped structures, and represent an increase in mobility over equivalently doped GaAs by about a factor of 20 at 10 K and by a factor of 2 at 300 K.     

GaAs-GaAlAs anti-Stokes light convertor

A multilayer heterojunction device has been manufactured and used for efficient anti-Stokes light conversion. The device consists of six layers: p GaAs, n GaAs, n GaxAl1?xAs, p GayAl1?yAs, p GaxAl1?xAs and p GaAs, essentially forming a GaAs photodiode coupled with a GaAlAs l.e.d. Avalanche multiplication of photoexcited carriers is used to increase the l.e.d. driving current.     

InGaAlP/GaAs Injection Lasers of the Orange Optical Range (~600 nm)

Semiconductors - Lasing in the orange spectral range (599–605 nm) is demonstrated for (AlxGa1 –x)0.5In0.5P–GaAs laser diodes grown by metalorganic vapor-phase epitaxy (MOVPE) on...     

GaAs/Al_xGa_(1-x)As超晶格中的纵光学声子模(英文)

The long wavelength optical phonon spectra of AlxGa1-xAs mixed crystals appear as "two-mode" behaviour, i.e. there are GaAs-like and AlAs-like optical branches simultaneously. Besides* the LO phonon dispersion curves of bulk GaAs and GaAs-like in AlxGa1-xAs mixed crystal are partly overlapped. Therefore, we expect, in GaAs/AlxGa1-xAs superlattices, that LO phonons are partly in confined modes while partly in folded one, and that AlAs-like modes are confined in AlxGa1-xAs layers.The samples of GaAs/AlxGa1-xAs superlattices were grown by MBE on (001) oriented semi-insulating GaAs substrates. Raman spectra were measured in the back-scattering geometry at room temperature. Only odd modes with B2 symmetry were observed for LO modes confined in the GaAs layer. This result is in agreement with the previous reports. In addition, AlAs-like LO modes confined in AlxGa1-xAs layers were observed for the first time.