Gallium Arsenide Substrates Research Articles

Исследование двухфотонного поглощения фемтосекундного ИК излучения методом «накачка – зондирование» в отражении от пластинки GaAs (001)

The reflection of probe infrared femtosecond radiation pulses from a gallium arsenide substrate of the (001) orientation in the presence of more powerful pump pulses of the same radiation with a peak power of up to 1 GW/cm2 was investigated. A Yb3+:KY(WO4)2 laser with a central wavelength of 1 035 nm, a repetition rate of 70 MHz, a pulse duration of 130 fs, and an average power of not more than 0.9 W worked in the GaAs transparency region. The experimental dependence of the recorded signal on the pump radiation intensity is in qualitative agreement with the model dependence for two-photon absorption. The results are important for the correct interpretation of reflectivity kinetics of quantum wells.

Micro-fabricated wideband band-stop filter using GaAs-based integrated passive device technology

This paper presents a new concept of implementing a micro-fabricated wideband band-stop filter on a gallium arsenide (GaAs) substrate using integrated passive device technology. The incorporation of an air-bridge structure was explored to enhance design flexibility and achieve excellent radio-frequency performance of the filter. A wideband band-stop filter was realized on a GaAs substrate, generating an insertion loss of − 0.37 dB and a return loss of − 38 dB with excellent attenuation of − 28.78 and − 22.27 dB, in the lower and the upper passband, respectively. The filter resonates at 10.72 GHz, occupying a die area of 2000 μm × 1540 μm. The selectivity of the filter is reflected by its tremendous suppression of out-of-band signals with the existence of attenuation poles in the vicinity of the resonance frequency. Experimental verification of the filter response demonstrates its potential use as an on-chip device operating in the X-band frequency spectrum.

Frequency and time domain analysis of surface acoustic wave propagation on a piezoelectric gallium arsenide substrate: A computational insight

A computational study of the electromechanical response of micro-structure engineered two port surface acoustic wave delay lines on gallium arsenide is presented. The influence on the results of geometrical, material, and mesh parameters is also discussed. Furthermore, experimental results are provided to validate the numerical study. The device consists of two interdigital transducers composed of 40, 80, and 120 pairs of electrodes, respectively, with a pitch [Formula: see text] and distant [Formula: see text]. In particular, a microwave burst of surface acoustic waves propagating on gallium arsenide is fully characterized including multiple transit effects. These results are of major interest for understanding the dynamical behavior of complex systems such as surface acoustic wave–based sensors or energy harvesting devices at the nano and microscale.

Integrated passive device fabricated and chip‐on‐board packaged filter employing mixed electric–magnetic coupling scheme

Compact and high-performance radio-frequency devices require several optimisation processes in the design, fabrication, and packaging, as well as a thorough reliability verification. The authors propose a compact planar dual-band bandpass filter comprising mixed electric-magnetic coupling open-loop resonators. To increase the coupling performance and minimise the structure size, the resonators were topologically optimised into both external stepped-impedance resonators and internal half-wavelength spiral resonators. Besides the electric length of the resonators, the centre frequencies and transmission zeros were tuned to the desired values by controlling the coupling coefficients and quality factors. Moreover, in their design, the in-band flatness and bandwidth can also be adjusted. To validate their approach, they fabricated a filter on a gallium arsenide substrate using the advanced-integrated passive device process. Then, the filter was packaged by attaching it to a printed circuit board using a chip-on-board technique. The measurement results were consistent with those obtained from a simulation. A series of tests verified that the utilised fabrication and packaging techniques notably enhance the device reliability and its long-term stability even in harsh environments.

Technology of production and magnetoelectric characteristics of multilayer structures nickel-tin on the gallium arsenide substrate

The technology of fabrication and the results of the magnetoelectric effect investigation in sandwich structure manufactured by galvanic deposition tin and nickel on the gallium arsenide substrate are presented. It is shown that the use of tin as an intermediate layer lead to reduces the mechanical stresses resulting on the interface nickel and gallium arsenide. It is possible to obtain qualitative structures with nickel layer thickness on the order of 100 microns. Experimental results of the frequency dependence of the magnetoelectric voltage coefficient in the region of electromechanical resonance are presented. The resonance value of the magnetoelectric voltage coefficient reached 40V/(cm·Oe) with the Q-factor ≌ 700, which significantly exceeds the characteristics of similar structures obtained by bonding.

The current–voltage and capacitance–voltage characterization of the Au/Methylene Blue/n-GaAs organic-modified Schottky diodes

We report the electrical properties of the Au/n–GaAs devices with and without thin organic interface layer. Methylene blue (MB) is a heterocyclic aromatic chemical compound with the molecular formula C16H18N3SCl. The MB layer was formed by spin coating technique on chemically cleaned gallium arsenide (GaAs) substrate. The current–voltage (I–V) and the frequency dependent capacitance–voltage (C–V) characteristics of the Au/MB/n–GaAs metal-insulator-semiconductor (MIS) and Au/n–GaAs metal-semiconductor (MS) devices have been investigated at room temperature. The MS and MIS devices I–V characteristics the showed a good rectification, and they were analyzed based on the thermionic emission (TE) theory. The ideality factor (n) and the barrier height (Φb(IV)) from the I–V characteristics was determined as 1.131±0.006 and 0.782±0.005 eV for MS device and 1.336±0.057 and 0.950±0.008 eV for MIS device, respectively. A Cheung’s method and modified Norde's function has been used to extract the parameters including the (Φb) and the series resistance (RS). Also the values of the barrier height obtained from the C–V measurements (Φb(CV)) of the MS and MIS was 0.863±0.034 eV and 1.187±0.093 eV, at 1 MHz, respectively.Distributions of the interface state density (Dit) of the MS and MIS devices were derivate from I–V and C–V measurements. Our results indicates that the Au/MB/n–GaAs device had lower interface state density values than the Au/GaAs device. Also non-saturated reverse bias current investigated by the using a Pole-Frenkel emission model. Furthermore, the optical and morphological properties of MB layer were investigated by the Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and UV-vis Spectrophotometer (UV-vis).Finally, we showed that, increasing Φb and decreasing Dit and improving electrical parameters of MIS devices indicates that, thin MB interface layer could prefer for modification of Au/n–GaAs devices.

Analysis of quantum-dot systems under thermal loads based on gradient elasticity

Since quantum-dot (QD) nanostructures in many applications are subjected to cyclic electrical and thermal loads, it is very important to analyze such nanostructures under transient thermal loads that affect the induced strains which in turn affects the response of the QD system. When the dimensions of the QDs are of the same order of magnitude as the material length scale, gradient elasticity theory should be used to account for the size-dependent behavior of such nano-sized QDs. In this work, a new finite element formulation for gradient-based thermo-electro-mechanical three-dimensional model of strained QDs in piezoelectric matrix under both static and dynamic thermal loads is developed. The proposed formulation requires only C0 shape functions since the original fourth order partial differential equation (PDE) is split into two PDEs of lower order. A unit cell of Indium Arsenide QD in a finite sized Gallium Arsenide (GaAs) substrate is analyzed. Results under dynamic loads demonstrate that the magnitude of the strain component in the thermal loading direction increases significantly with the thermal shock time. On the other hand, at a fixed time, the magnitude of the induced field quantities, such as the strain, decreases remarkably with increasing the size effect parameter. Given that large lattice mismatch induced strain fields are located in or near the QD regions, these newly observed features need to be carefully considered when designing such QD nanostructures.

Dynamically tunable dendritic graphene-based absorber with thermal stability at infrared regions

The infrared polarization-insensitive absorber, which is composed of dendritic metal, graphene layer, silicon dioxides layer, gallium arsenide substrate, and metal plate, is investigated theoretically and numerically. The tunability can be realized by loading a graphene layer into the structure. The position of absorption peak can be tuned by manipulating the graphene’s Fermi energy. Compared with the previously reported graphene-based absorbers, the system has the advantage of temperature-independent high absorption. The results indicate that the proposed absorber can be used in the applications of the refractive index sensor with a sensitivity of 587.8 nm/refractive index unit and temperature-insensitive infrared absorber.

Analysis of Dispersion Characteristics of Rayleigh Waves in Nanostructured Thin Films

The present study aims to theoretically analyze the dispersion characteristics of Rayleigh waves and verify the results through experiments. Raleigh waves are generated by scanning acoustic microscope, which are used to evaluate the thickness of thin films and the material characteristics of the samples. The transfer matrix method was used in the theoretical analysis of Rayleigh wave dispersion in thin films with slow-on-fast and fast-on-slow structures. To verify the dispersion diagram derived from the analysis, the e-beam evaporation and plasma-enhanced chemical vapor deposition technique was applied to fabricate slow-on-fast and fast-on-slow thin films of varying thicknesses. Slow-on-fast structures were created by depositing nickel (Ni) films on silicon (Si) substrates; fast-on-slow structures were produced by depositing silicon nitride (Si₃N₄) on gallium arsenide (GaAs) substrates. The scanning acoustic microscope used V(z) curves to precisely measure the velocity of the Rayleigh waves. This was to evaluate their dispersion depending on the thickness of each film. A comparison of the measured velocities against the theoretical dispersion diagram resulted in an error rate of less than 6% in the slow-on-fast structure and less than 10% in the fast-on-slow structure. In conclusion, this study confirmed that the theoretically derived dispersion characteristics correspond well with those observed in actual thin films, thereby suggesting the potential use of theoretical dispersion diagrams in evaluating the thickness and material characteristics of thin films.

Epsilon-near-zero enhanced plasmonic Brewster transmission through subwavelength tapered metallic gratings

Recently, epsilon-near-zero (ENZ) materials have been employed to stimulate light funnelling enhancement through a subwavelength metallic channel. In this paper, we present a study of enhanced optical transmission through subwavelength metallic gratings deposited on ENZ material and gallium-arsenide (GaAs) substrate. We propose to carve periodically tapered slits on the metallic grating to enable the impedance matching at the entrance and exit faces and thus enhance the light transmission at the plasmonic Brewster angle. The optimal grating geometry provides around 80% average transmission over a broad bandwidth from 5 THz to 20 THz at the incident Brewster angle of 76°. Our study extends potential practical applications of ENZ materials for integrated photonics.

Magnetoelectric effect in ferromagnetic-semiconductor layered composite structures

The results of magnetoelectric effect experimental studies in two different structures based on piezoelectric semiconductor gallium arsenide are presented. The monolithic structure consisted of a gallium arsenide substrate with deposited nickel layer (GaAs-Ni), and the composite structure contained a semiconductor substrate with an amorphous magnetic alloy (GaAs-Metglas) ribbon glued on one side. A quality factor Q ≈ 23500 and magnetoelectric coefficient of 316 V/Oe.cm were achieved at the frequency of planar acoustic oscillations for GaAs-Ni structure at room temperature.

ZnO/GaAs heterojunction solar cells fabricated by the ALD method

Zinc oxide is nowadays widely investigated in many different science areas. In particular, this wide band gap semiconductor is valued due to its possible use in transparent electronics as TCO (Transparent Conductive Oxide) and/or as ARC (Antireflective Coating). In other applications, ZnO can also play active role in light source devices, UV detectors, solar cells, etc. In this experiment we focused on zinc oxide applicability assessment in solar cell devices. ZnO as well as its Al-doped form AZO (Aluminum doped Zinc Oxide) were examined in view of their use both as TCO and the n-type partner for the p-type gallium arsenide (GaAs) substrate, that resulted in creation of the p-n heterojunction-based photovoltaic device. In order to deposit both ZnO as well as AZO layers, the ALD (Atomic Layer Deposition) method was applied.

The influence of the chemical and physical component of the plasma etching of the surface of gallium arsenide on the etching rate in the chloride plasma of the combined discharge

In this paper, experimental studies were carried out on the formation of a microrelief on the surface of gallium arsenide substrates. The surface was modified by the method of plasma etching. Etching was carried out in a medium of chloride gas. In the work, the etching rates of the surface of gallium arsenide depend on the power of the inductively coupled plasma source. The etching rate of gallium arsenide was 28.2 nm / min, 24.9 nm / min, 27.8 nm / min, at inductively coupled plasma power values of 200 W, 400 W and 600 W. In the same work, the patterns of etching rate of gallium arsenide surface Taking into account the capacity of the capacitive plasma and the voltage of the shift. The etching rate of gallium arsenide was 516.7 nm / min, 559.5 nm / min, 603.3 nm / min, with capacitive plasma power values of 10 W, 35 W and 70 W, respectively. These results can be used to form a modified surface for the subsequent epitaxial growth of quantum dots based on gallium arsenide.

Effect of thicknesses of InP epilayers on InP/GaAs heterostructure

InP epilayers with different thicknesses were grown on GaAs substrates at a low temperature by using metalorganic chemical vapor deposition. Atom force microscope and double‐crystal X‐ray were carried out to investigate the morphology and the crystal quality. Transmission electron microscopy was performed to characterize the microstructure and morphology. It was found that with the epilayer thicknesses increased, the crystal quality was improved and the dislocations in epilayers were decreased. Moreover, the sample that has 150‐nm InP epilayer could observe large numbers of antidislocations in the gallium arsenide substrate. The formation mechanism of antidislocations was also discussed with the analysis of crystal structure and surface morphology. Furthermore, we proposed a mechanism to explain the motion and the reaction of antidislocations.

Structural and optical studies of thin films of aluminum nitride grown via ion-plasma sputtering on gallium arsenide substrates with different orientations

IR and UV spectroscopy is used to study the properties of nanostructured aluminum nitride films obtained via reactive ion-plasma sputtering on GaAs substrates with different orientations. Nanostructured thin (100–200 nm) films of cubic aluminum nitride with optical bandgaps of ~5 eV and refractive indices varying from 1.6 to 4.0 in the wavelength range of ~250 nm are fabricated. Growth on a misoriented GaAs(100) substrate (4° with respect to the [110] plane) makes it possible to synthesize AlN films with smaller grains and higher refractive indices (n ~ 4). It is shown that misoriented GaAs substrates allow us to control the morphology, surface composition, and optical functional characteristics of AlN/GaAs heterophase systems.

Characterization of Gallium Indium Phosphide and Progress of Aluminum Gallium Indium Phosphide System Quantum-Well Laser Diode.

Highly ordered gallium indium phosphide layers with the low bandgap have been successfully grown on the (100) GaAs substrates, the misorientation toward [01−1] direction, using the low-pressure metal organic chemical vapor deposition method. It is found that the optical properties of the layers are same as those of the disordered ones, essentially different from the ordered ones having two orientations towards [1−11] and [11−1] directions grown on (100) gallium arsenide substrates, which were previously reported. The bandgap at 300 K is 1.791 eV. The value is the smallest ever reported, to our knowledge. The high performance transverse stabilized AlGaInP laser diodes with strain compensated quantum well structure, which is developed in 1992, have been successfully obtained by controlling the misorientation angle and directions of GaAs substrates. The structure is applied to quantum dots laser diodes. This paper also describes the development history of the quantum well and the quantum dots laser diodes, and their future prospects.

D-band Waveguide Transition Based on Linearly Tapered Slot Antenna

Abstract In this work, an on-chip Monolithic Microwave Integrated Circuit (MMIC) to waveguide transition is realized based on Linearly Tapered Slot antenna (LTSA) structure. The antenna is implemented on a 50-um-thick Gallium Arsenide (GaAs) substrate and placed in the E-plane of an air-filled D-band waveguide. The transition shows a maximum insertion loss of 1 dB across the frequency range 110–170 GHz. The average return loss of the transition is −15 dB and the minimum is −9 dB. The structure occupies an area of 0.82×0.6 mm2. The transition provides low-loss wide-band connectivity for millimeter-wave systems and addresses integration challenges facing systems operating beyond 100 GHz.

The magnetoelectric effect in nickel–GaAs–nickel structures

We have experimentally studied the magnetoelectric (ME) effect in structures obtained by the electrolytic deposition of nickel onto gallium arsenide substrates. It is established that the use of a pre-deposited Ni–Au–Ge–Ni buffer sublayer significantly improves the adhesion of electroplated nickel to substrate. The resulting Ni–GaAs–Ni structures are featuring both linear and nonlinear ME effects with respect to the alternating magnetic field. Both these effects exhibit a resonance character, the resonance frequency of the nonlinear ME effect being two times lower than that for the linear effect.

Influence of thickness on crystallinity in wafer-scale GaTe nanolayers grown by molecular beam epitaxy

We grew wafer-scale, uniform nanolayers of gallium telluride (GaTe) on gallium arsenide (GaAs) substrates using molecular beam epitaxy. These films initially formed in a hexagonal close-packed structure (h-GaTe), but monoclinic (m-GaTe) crystalline elements began to form as the film thicknesses increased to more than approximately 90 nm. We confirmed the coexistence of these two crystalline forms using x-ray diffraction and Raman spectroscopy, and we attribute the thickness-dependent structural change to internal stress induced by lattice mismatch with the substrate and to natural lattice relaxation at the growth conditions.

31% European InGaP/GaAs/InGaAs Solar Cells for Space Application

We report a triple junction InGaP/GaAs/InGaNAs solar cell with efficiency of ~31% at AM0, 25 °C fabricated using a combined molecular beam epitaxy (MBE) and metal-organic chemical vapour deposition (MOCVD) processes. The prototype cells comprise of InGaNAs (Indium Gallium Nitride Arsenide) bottom junction grown on a GaAs (Gallium Arsenide) substrate by MBE and middle and top junctions deposited by MOCVD. Repeatable cell characteristics and uniform efficiency pattern over 4-inch wafers were obtained. Combining the advantages offered by MBE and MOCVD opens a new perspective for fabrication of high-efficiency space tandem solar cells with three or more junctions. Results of radiation resistance of the sub-cells are also presented and critically evaluated to achieve high efficiency in EOL conditions.