Gallium Arsenide Material Research Articles

Real, imaginary and complex branches of Lamb waves in p-type piezoelectric semiconductor GaAs plate: Numerical and experimental investigation

First, we experimentally measure the concentration of holes of the piezoelectric semiconductor (PSC) Gallium arsenide (GaAs) material based on the Hall effect measurement. We then numerically calculate the Lamb wave characteristics in a p-type PSC GaAs plate using this measured value of the concentration of holes (estimated at approximately p0=3.5431×1025m−3). To guarantee the coupling effect that makes the Lamb wave a piezo-active wave, the GaAs crystal is oriented in a specific orientation of (110) plane. Ordinary differential equation (ODE) method is employed to calculate the dispersion curves, 3D view of the mechanical displacements, 3D view of the electric potential and 3D view of the concentrations of holes. Results show that the appearance of the complex branches of the Lamb modes coincides with the vanishing of the imaginary part of the wavevector (Im(k1)) to zero, which is a very remarkable finding that has not been discussed in previous studies. Meanwhile, these complex branches start exactly at the point of Zero-group-velocity (ZGV). Moreover, the present work highlights the hole drift characteristics of PSC GaAs and provides a critical comparative discussion with those published by (Zhu et al., 2018) for the PSC ZnO plate. Accordingly, the “Screening effect” phenomenon that is based on the positive holes in the negative electric potential region is discussed. The present results provide a theoretical and fundamental guidance on the development of smart devices based on the PSC GaAs material.

A realistic assessment of the prospect that silicon be replaced by other materials for IC application

Silicon is the most significant material in the semiconductor industry, and the whole semiconductor industry is established on silicon materials. Silicon accounts for about a third of the value of the material used to make the entire wafer. However, with the development of the semiconductor industry and integrated circuit chips, the requirements for semiconductor materials are also increasing. In some application scenarios, silicon is gradually unable to meet peoples higher requirements. For example, in high-frequency applications, the characteristics of silicon may be limited. At higher frequencies, the conductivity of silicon may not be ideal, leading to signal delay and performance loss. Therefore, finding alternative materials for silicon has become one of the current research topics for scientists, in order to solve some problems that silicon cannot solve under specific conditions. In this article, we mainly explore the characteristics and advantages of carbon nanotubes, gallium arsenide, and silicon carbide materials to analyze the feasibility of these materials replacing silicon in the field of integrated circuits.

Effects ofAs8structure formation on the surface morphology and internal microstructure of GaAs thin films.

Gallium arsenide (GaAs) materials have the advantages of high electron mobility, electron saturation drift rate, and other irreplaceable semiconducting properties. They play an important role in the electronics, solar and other fields. However, during GaAs film sedimentary growth, As atoms can undergo segregation to formAs8clusters because of the influence of external factors, which affect the surface morphology and internal structure of these films. In this study, a series of investigations on the deposition and growth of GaAs crystal films were performed. Additionally, the deposition and growth of GaAs thin films were simulated using molecular dynamics. The influence of As8clusters on the surface morphology and internal structure of GaAs films at different incidence angles, velocities and substrate temperatures was studied by using 'defect analysis technology' and 'diamond structure identification' in open source software, along with surface roughness and radial distribution function. Results show that with increasing incident angle, the number ofAs8clusters decreases and film density increases. Increasing incident velocity increases the irregular movement ofAs8clusters in air, and their deposition on the film surface affects the morphology of the film, and the surface roughness increases first and then decreases. Additionally, we investigated the effect of different substrate temperatures on the film surface. Results show that at a substrate temperature of 1173 K, the number ofAs8clusters in the film decreases or the As8clusters disappear, heterogeneous nucleation occurs in the film, and the crystallization rate increases. Although the dislocation line associated with nucleation may affect the mechanical and optical properties of the film, it considerably reduces the annealing effort after the deposition and growth.

A Novel Pulse Compression Diode for Picosecond Pulse Generation

A novel pulse compression diode capable of generating high-voltage, picosecond pulses is introduced. The design concept and technical means of the novel diode based on semi-insulating gallium arsenide (SI-GaAs) materials are described, followed by the presentation of its static characteristics with three unique operating states. Typical output rise time for the novel diode with self-breakdown is limited to a few nanoseconds (1–2 ns). The basic physical mechanism affecting the fast conduction of the device is then analyzed, and the electrode structure is optimized as a consequence. Finally, a test circuit with a MOSFET as a preswitch is used as an example to verify the compression characteristics of the modified device. The experimental results show that the pulse front is sharpened from 32 ns to 853 ps and the full-width at half-maximum (FWHM) is sharpened from 120 to 2.1 ns by the pulse compression diode without extra triggering. Lifetime measurement experiments were conducted at a pulse repetition frequency of 100 Hz, revealing no instances of switch failures or malfunctions. The novel pulse compression diode has great potential for various applications, including in national defense, industrial, and medical sectors, due to its fast response, long lifetime, high reliability, and ease of series–parallel connection.

Monolithically Integrated Extended Cavity Diode Laser with 32 kHz 3 dB Linewidth Emitting at 1064 nm

AbstractThe spectral linewidth of semiconductor lasers is a crucial performance parameter in a growing number of applications. A common method to improve the coherence of the laser relies on increasing the optical cavity length by an extended section without gain material. Here, this extended cavity diode laser (ECDL) concept is realized in a monolithic device at 1064 nm wavelength. This is accomplished by applying a two‐step epitaxy in the aluminum gallium arsenide material system to selectively remove the active layers in a specific section of the chip. The extended passive section decreases the 3 dB linewidth to 32 kHz at 1 ms integration time. A direct comparison between the performance of the monolithic ECDL and a distributed Bragg reflector laser from the same wafer demonstrates the feasibility of the approach. The results in terms of frequency noise, side mode suppression ratio, injection current threshold, and slope efficiency show that the passive section reduces the laser linewidth while the additional interfaces within the laser cavity created by the manufacturing process do not deteriorate the electro‐optical properties or frequency stability. This opens the possibility for the realization of gallium arsenide based photonic integrated circuits by monolithically combining active and low‐loss passive waveguides.

ARM based smart energy management system for home automation

Nowadays the power saving system is very essential in every house. This smart saving system mainly targets on the potential of home automation smart systems. Automation is a huge range of technology that minimizes the human involvement in the system. The major goal of this project is to minimize the power utilization and whenever the door was opened the devices will gets activated and works according to the inside, temperature and light intensity. The home devices like light and fan will automatically adjust to their intensity and also the speed level. For opening the door the access is given to the authorized person and it depends on the technology called Internet of Things [IOT] concept.i.e. the door opening will be controlled by mobile application or Web server. Therefore, the status updates of light and fan will be monitored through the Internet of Things [IOT] technology. All the electronic components used in this project are silicon, germanium, and gallium-arsenide materials.

Exception of terahertz quantum cascade laser based on new material systems

<p indent=0mm>Terahertz (THz) waves have potential applications in biomedical, astronomy, national defense and other fields. The THz radiation source is a key component for the application of THz technology. The semiconductor-based electrically pumped THz quantum cascade laser (QCL) has attracted the attention of researchers due to its high output power, tunable frequency, and all-solid-state advantages. However, for a long time, the lower operating temperature of the traditional THz QCL based on gallium arsenide (GaAs) material system has restricted its wide application. Through the longitudinal optical (LO) phonons in different materials and their roles in the THz wave emission process, finding a new material system for the preparation of THz QCL is a feasible solution to improve the operating temperature of the device. This article reviews the recent research progress of gallium nitride (GaN) and zinc oxide (ZnO) based THz QCL.

Influence of piezoelectric phonons on the magneto optical transition linewidth in GaN and GaAs

We compare piezoelectric phonon scattering mechanism with optical phonon one in both Gallium arsenide (GaAs) and Gallium nitride (GaN) materials of a quantum well through the their contribution to the magneto-optical transition linewidths (MOTLWs). Applying the projection-operator and the profile methods to compute the magneto-optical conductivity tensor (MOCT), magneto-optical absorption power (MOAP), and MOTLWs. Numerical calculation results show that the MOTLWs increase as the temperatures and the magnetic fields increase, but decrease as the electron density and the well width increase for both GaN and GaAs materials. In particular, the MOTLWs due to piezoelectric phonons vary sharper and have larger value than they do due to optical phonons in both GaN and GaAs materials, and the MOTLWs of GaN are larger than those of GaAs for both piezoelectric and optical phonon scattering mechanisms. As small enough quantum-well-width, the piezoelectric phonon modes play an important role and they should be considered in studying the magneto optical transition properties in low-dimensional electron systems. • Influence of piezoelectric phonons on the magneto-optical transition linewidths (MOTLWs) in GaN and GaAs is studied. • MOTLWs are affected strongly by temperature, magnetic field, electron density, and well width. • MOTLWs for piezoelectric phonon are compared with those for optical phonon in both GaN and GaAs. • MOTLWs of GaN are compared with those of GaAs for both piezoelectric and optical phonons. • Influence of piezoelectric phonon on the MOTLWs is considerable and cannot be neglected.

Investigation and optimization of light trapping through hexagonal-shaped nanopillar (NP) array of indium gallium arsenide material based photodetector

Nanopillar arrays over the photodetector’s surface attribute an enhanced coupling efficiency of incident light due to its various light trapping mechanisms that contribute towards high-resolution optical detection. This paper reports the analytical investigation of the performance of Indium Gallium Arsenide material based hexagonal-shaped nanopillar (NP) array deployed over the 5 um × 5 um detector’s front surface for high photodetection infrared applications. The proposed structure exhibits an optimum 98% overall absorption of the incoming light. High EQE of about 75% and responsivity of 0.93 A/W has been obtained at 1.55 um operating wavelength with a minimum detector’s depletion width of 0.7 um at 1 mw optical input power.

The Design of Terahertz Monolithic Integrated Frequency Multipliers Based on Gallium Arsenide Material.

A global design method for a terahertz monolithic integrated frequency multiplier is proposed. Compared with a traditional independent design, the method in this paper adopts overall optimization and combines the device with the circuit design. The advantage is that it provides a customized design for frequency multipliers according to specifications. On the basis of the gallium arsenide process of the Institute of Microelectronics, Chinese Academy of Sciences, two types of Schottky diodes have been developed to meet the needs of different designs. On the one hand, a Schottky diode with a 3 μm junction’s diameter was used in the design of the 200 GHz balanced doubler and, on the other hand, a diode with a 5 μm diameter was used in the 215 GHz unbalanced tripler. The measured results indicated that the output power of the doubler was more than 250 μW at 180~218 GHz, and the maximum was 950 μW at 198 GHz when driven with 12.3 mW, whereas that of the tripler was above 5 mW at 210~218 GHz and the maximum exceeded 10 mW. Such frequency multiplier sources could be widely used in terahertz imaging, radiometers, and so on.

Current Status and Future Trends of Photonic-Integrated FBG Interrogators

In this paper, we present an overview of the current efforts toward integration on chip of fiber Bragg grating (FBG) sensor interrogators. Different photonic-integration platforms are discussed, including monolithic planar lightwave circuit technology, silicon on insulator (SOI), indium phosphide, and gallium arsenide material platforms. Furthermore, various possible techniques for wavelength metering and methods for FBG multiplexing are discussed and compared in terms of resolution, dynamic performance, multiplexing capabilities, and reliability. The use of linear filters, array waveguide gratings (AWG) as multiple linear filters, and AWG-based centroid signal processing techniques are presented as well as interrogation techniques based on tunable microring resonators and Mach-Zehnder interferometers for phase sensitive detection. FBG sensor interrogation based on SOI platform using active and passive phase sensitive detection is also described, demonstrating specifically the potential of passive phase demodulation for high-speed dynamic strain measurements. This paper finally presents the challenges and perspectives of photonic integration to address the increasing requirements of several industrial applications.

Effect of Growth Temperature on GaAs Solar Cells at High MOCVD Growth Rates

Increasing epitaxial growth rate is an important path toward III-V solar cell cost reductions; however, photovoltaic device performance has been shown to degrade with increasing growth rate. In this study, gallium arsenide (GaAs) material has been deposited via metal-organic chemical vapor deposition (MOCVD) at growth rates varying between 14 and 60 μm/h. Deep-level transient spectroscopy is utilized to elucidate an exponential rise in EL2 trap density as a function of growth rate when all other growth conditions are held constant. Evidence is provided that this EL2 defect is responsible for limiting the Shockley-Read-Hall (SRH) lifetime of very high growth rate solar cells. The effect of growth temperature on devices at high growth rate is subsequently investigated as a strategy to reduce trap density and improve solar cell performance. From this investigation, EL2 trap density is suppressed, and single-junction on-substrate GaAs solar cells grown at 60 μm/h are reported with 1.01 V 1-sun open-circuit voltage and 23.8% AM1.5G efficiency.

An exploratory review on some inorganic materials and structure of solar cells

Because of the pollution-free, renewable and clean energy of solar cells, more and more inorganic materials are used for solar cell research. Zinc oxide, gallium arsenide, perovskite and graphene materials are studied in this paper as the representatives of inorganic compounds or materials; we discuss the parameters such as band structure, density of states of doping and structure of materials, and their effects on the photoelectric conversion efficiency are also reviewed. Study results will provide some reference for further designing and manufacturing solar cells.

The Study of 0.34 THz Monolithically Integrated Fourth Subharmonic Mixer Using Planar Schottky Barrier Diode

A planar Schottky barrier diode with the designed Schottky contact area of approximately 3 μm2 is developed on gallium arsenide (GaAs) material. The measurements of the developed planar Schottky barrier diode indicate that the zero-biased junction capacitance Cj0 is 11.0 fF, the parasitic series resistance RS is 3.0 Ω, and the cut off frequency fT is 4.8 THz. A monolithically integrated fourth subharmonic mixer with this diode operating at the radio frequency (RF) signal frequency of 0.34 THz with the chip area of 0.6 mm2 is implemented. The intermediate frequency (IF) bandwidth is from DC to 40 GHz. The local oscillator (LO) bandwidth is 37 GHz from 60 to 97 GHz. The RF bandwidth is determined by the bandwidth of the on chip antenna, which is 28 GHz from 322 to 350 GHz. The measurements of the mixer demonstrated a conversion loss of approximately 51 dB.

High-performance green flexible electronics based on biodegradable cellulose nanofibril paper.

Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials.

The roles of the temperature on the structural and electronic properties of deep-level VAsVGa defects in gallium arsenide

The roles of temperature on the structural and electronic properties of VAsVGa defects in gallium arsenide have been studied by using ab-initio molecular dynamic (MD) simulation. Our calculated results show that the relatively stable quaternary complex defect of GaAsAsGaVAsVGa can be converted from the VAsVGa complex clusters defect between 300K and 1173K; however, from 1173K to 1373K, the decomposition of the complex defect GaAsAsGaVAsVGa occurs, turning into a deep-level VAsVGa cluster defect and an isolated AsGa antisite defect, and relevant defect of GaAs is recovered. The properties of GaAsAsGaVAsVGa defect has been studied by first-principles calculations based on hybrid density functional theory. Our calculated results show that the GaAsAsGaVAsVGa belongs to EL2 deep-level defect in GaAs. Thus, we reveal that the temperature has an important effect on the microstructure of deep-level defects and defect energy level in gallium arsenide that EL2 and EL6 deep-level defects have a certain correlation, which means they could transform into each other. Controlling temperature in the growth process of GaAs could change the microstructure of deep-level defects and defect energy levels in gallium arsenide materials, whereby affects the electron transport properties of materials.

Gallium arsenide (GaAs) quantum photonic waveguide circuits

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9±1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6±1.3% and 84.4±1.5% respectively were demonstrated in Mach–Zehnder interferometers exploiting the electro-optic Pockels effect. This work paves the way for a fully integrated quantum technology platform based on the GaAs material system.

Maximizing band gaps in two-dimensional photonic crystals in square lattices

This paper is devoted to a numerical algorithm for the maximization of band gaps in two-dimensional photonic crystals in square lattices. We first apply the finite element method to solve the eigenvalue problem, then use the piecewise constant level set (PCLS) method to maximize the band gaps. The PCLS method is very powerful for representing and modeling regions of different structures. Extremely large gaps are realized with gallium arsenide material, for transverse magnetic field (TM), transverse electric field (TE), and for complete band gaps. When the mean gap frequency is below 1, the biggest gap is about 0.2922 for the TE.

Photonic crystal with complex unit cell for large complete band gap

A novel two-dimensional complex photonic crystal with dielectric rods and veins in square and honeycomb lattice is presented to achieve large complete band gaps. The rods with different symmetries, shapes, orientations, and sizes are investigated numerically. The sizes of gaps are intensively affected by these geometric parameters. Extremely large gaps are realized by the parameter optimization with gallium arsenide material. The scattering of veins is more dominant than that of rods which demonstrates the validity of the complex photonic crystal structures. Furthermore, an excellent wide region of dielectric rods and veins, where the sizes of gaps are universally large, is found in square and honeycomb lattice, respectively.

Determination of ionic and pure electronic contributions to the electro-optic coefficient of cadmium telluride and gallium arsenide single crystals

High electro-optic figure of merit n 0 3 r 41 and the absence of natural birefringence make semi-insulating gallium arsenide (GaAs) and cadmium telluride (CdTe) attractive materials for the fabrication of electro-optical devices. In this context we characterized both acoustic and optical phonon contributions to the electro-optic coefficient of CdTe and GaAs. Accurate measurements of n 0 3 r 41 as a function of modulation frequency and temperature were carried out on CdTe:In and GaAs crystal at 1.5 μm. For CdTe, to the best of our knowledge, this is the first time that a contribution to the electro-optic coefficient due to optical phonons has been determined. A positive value for the ionic contribution, due to optical phonons in GaAs, is obtained, in disagreement with that previously inferred from Raman scattering efficiency measurements. The pure electronic contribution was then isolated, and the second-order non-linear optical coefficient was derived. The latter was compared to previously reported data from non-linear wavelength conversion measurements.