65-145 GHz InP MMIC HEMT medium power amplifiers
In this paper, we present two MMIC power amplifier designs utilizing InP HEMT technology.
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In this paper, we present two MMIC power amplifier designs utilizing InP HEMT technology.
We present results of developments of low noise millimeter wave receivers for space applications utilizing InP HEMT monolithic microwave integrated circuts (MMICs).
We report common base power amplifiers designed for 140-220 GHz frequency band in InP mesa double heterojunction bipolar transistor (DHBT) technology.
We report a single stage tunded amplifier that exhibits 7 dB small signal gain at 176 GHz. Common Base topology is chosen as it has the best maximum stable gain (MSG) in this frequency band when compared to common emitter and common collector topologies. The amplifiers are designed and fabricated in InP mesa double heterojunction bipolar transistor (DHBT) technology.
In this article, a 220-GHz direct detection polarimetric receiver is reported. This polarimetric receiver is intended for sensing of the microphysical properties of cloud ice in the earth's upper atmosphere. In the article, we report the measured RF performance, including RF gain of approximately 35 dB per channel and integrated noise figure of the receiver. The noise figure is measured to be 5.1 dB for the horizontally polarized channel and 5.4 dB for the vertically polarized channel. The receiver measures only 1.8 cm × 3.0 cm × 6.4 cm and has a total regulated dc power consumption of 520 mW. This article represents the first 220-GHz polarimetric direct detection receiver and is enabled by an advanced 25-nm indium phosphide (InP) HEMT monolithic microwave integrated circuit (MMIC) technology.
All-optical 1:4 and 1:8 demultiplexers are designed and demonstrated using the process of photon absorption that is induced using an external optical pumping of wavelength 532 nm in InGaAsP–InP add-drop microring resonators. The 1:4 demultiplexer is designed with two cascaded optical microring resonators (OMRRs) and 1:8 demultiplexer is designed with four OMRRs. The mathematical modeling is pursued in Z-domain. The delay has been reduced by implementing a three level parallel circuit for 1:8 demultiplexer. The nonlinearity that occurs as a resonance frequency shift in OMRR due to photon energized electron–hole pairs is used to realize the optical switching operation of OMRR. The simulation is carried using MATLAB. The circuit has less propagation delay, fast switching time and can be integrated on CMOS photonic chips.
Semiconductor nanocrystals (NCs) offer actualized and prospective utility in optoelectronic technologies, yet key aspects of their thermal and vibrational behaviors remain unresolved. Compared with bulk crystals, heat dissipation involving NCs can differ substantially owing to pervasiveness of interfacial scattering, phonon confinement, and relaxed phonon momentum selection rules, as well as influences of ligands. Here, in addition to transient absorption, we use femtosecond stimulated Raman spectroscopy to track nonequilibrium optical-phonon dynamics in InP NCs capped with myristic acid ligands and compare the same particles coated with a ZnS shell. We identify distinct phonon decay pathways in ligand-capped versus ZnS-shelled NCs. Increasing the excitation density and introducing the ZnS shell measurably modify optical-phonon lifetimes, whereas phonon formation times remain largely unchanged. In addition, we observe phonon mode softening in ligand-capped nanocrystals, consistent with lattice expansion. Together, these results demonstrate that core–shell structures can strongly govern nanocrystal thermal dissipation pathways and should be considered a key design parameter for optoelectronic operation.
We study the carrier relaxation dynamics in Ga{sub 1-y}In{sub y} N{sub 0.03}As{sub 0.97} layers grown on InP substrate by molecular beam epitaxy. This dilute nitride semiconductor is a potential candidate for ultrafast components such as photoconductive terahertz devices driven at 1.55 {mu}m wavelength. Carrier lifetimes are measured by pump-probe experiments at 1550 nm wavelength and the shortest carrier lifetime is 2.6 ps under photoexcitation with {approx}4.2 {mu}J/cm{sup 2}. We observe two contributions in the differential transmittance decay. These contributions are discussed in terms of photocarrier recombination processes.
We report the self-assembly of InAs ring complexes on InP (100) substrates by droplet epitaxy. Single-ring, ring-disk complex, and concentric double-ring structures were formed by controlling the As beam flux and substrate temperature. A clear photoluminescence signal was detected in a sample where InAs rings were embedded in InGaAs.
Epitaxial layers of the topological insulator Bi{sub 2}Se{sub 3} have been grown by molecular beam epitaxy on laterally lattice-matched InP(111)B substrates. High resolution X-ray diffraction shows a significant improvement of Bi{sub 2}Se{sub 3} crystal quality compared to layers deposited on other substrates. The measured full width at half maximum of the rocking curve is {Delta}{omega}=13 arc sec, and the ({omega}-2{theta}) scans exhibit clear layer thickness fringes. Atomic force microscope images show triangular twin domains with sizes increasing with layer thickness. The structural quality of the domains is confirmed on the microscopic level by transmission electron microscopy.
We report the growth of single-domain epitaxial Bi{sub 2}Se{sub 3} films on InP(111)A substrate by molecular-beam epitaxy. Nucleation of Bi{sub 2}Se{sub 3} proceeds at steps, so the lattices of the substrate play the guiding role for a unidirectional crystalline film in the step-flow growth mode. There exists a strong chemical interaction between atoms at the heterointerface, so the growth does not follow the van der Waals epitaxy process. A mounded morphology of thick Bi{sub 2}Se{sub 3} epilayers suggests a growth kinetics dictated by the Ehrlich-Schwoebel barrier. The Schubnikov de Haas oscillations observed in magnetoresistance measurements are attributed to Landau quantization of the bulk states of electrons.
The interfacial chemistry of the native oxide and chemically treated InP samples during atomic layer deposition (ALD) HfO{sub 2} growth at 250 Degree-Sign C has been studied by in situ X-ray photoelectron spectroscopy. The In-oxide concentration is seen to gradually decrease on the native oxide and acid etched samples. No significant changes of the P-oxide concentrations are detected, while the P-oxides chemical states are seen to change gradually during the initial cycles of ALD on the native oxide and the chemically treated samples. (NH{sub 4}){sub 2}S treatment strongly decreases In-oxide and P-oxide concentrations prior to ALD and maintains low concentrations during the ALD process.
This article presents a characterization of the damage caused by energetic beams of electrosprayed nanodroplets striking the surfaces of single-crystal semiconductors including Si, SiC, InAs, InP, Ge, GaAs, GaSb, and GaN. The sputtering yield (number of atoms ejected per projectile's molecule), sputtering rate, and surface roughness are measured as functions of the beam acceleration potential. The maximum values of the sputtering yields range between 1.9 and 2.2 for the technological important but difficult to etch SiC and GaN respectively, and 4.5 for Ge. The maximum sputtering rates for the non-optimized beam flux conditions used in our experiments vary between 409 nm/min for SiC and 2381 nm/min for GaSb. The maximum sputtering rate for GaN is 630 nm/min. Surface roughness increases modestly with acceleration voltage, staying within 2 nm and 20 nm for all beamlet acceleration potentials and materials except Si. At intermediate acceleration potentials, the surface of Si is formed by craters orders of magnitude larger than the projectiles, yielding surface roughness in excess of 60 nm. The effect of projectile dose is studied in the case of Si. This parameter is correlated with the formation of the large craters typical of Si, which suggests that the accumulation of damage following consecutive impacts plays an important role in the interaction between beamlet and target.
The microstructure of (001) InP crystals scratched with a sharp diamond tip depends strongly on the scratching direction. The scratch surface is found to conform to the radius of curvature of the tip (∼60 nm) by the formation of atomic crystal steps produced by dislocation glide along (111) planes. 〈110〉 scratches lead to coherent local crystal lattice movement and rotation causing deep dislocation propagation into the crystal and irregular pileups at the sides of the scratch surface. 〈100〉 scratches lead to incoherent lattice movement causing dislocation locking that inhibits their propagation and results in regular pileups.
The interfacial chemistry of thin Al (∼3 nm) and Hf (∼2 nm) metal films deposited by electron beam (e-beam) evaporation on native oxide InP (100) samples at room temperature and after annealing has been studied by in situ angle resolved X-ray photoelectron spectroscopy and low energy ion scattering spectroscopy. The In-oxides are completely scavenged forming In-In/In-(Al/Hf) bonding after Al and Hf metal deposition. The P-oxide concentration is significantly decreased, and the P-oxide chemical states have been changed to more P-rich oxides upon metal deposition. Indium diffusion through these metals before and after annealing at 250 °C has also been characterized. First principles calculation shows that In has lower surface formation energy compared with Al and Hf metals, which is consistent with the observed indium diffusion behavior.
The solid solutions InP{sub x}As{sub 1−x} were investigated before and after irradiation with fast neutrons and electrons. By use of the technology developed by us, we created the radiation-resistant materials enduring the high dose of hard radiation.
Ultrafast switching with low energies is demonstrated using InP photonic crystal nanocavities embedding InGaAs surface quantum wells heterogeneously integrated to a silicon on insulator waveguide circuitry. Thanks to the engineered enhancement of surface non radiative recombination of carriers, switching time is obtained to be as fast as 10 ps. These hybrid nanostructures are shown to be capable of achieving systems level performance by demonstrating error free wavelength conversion at 10 Gbit/s with 6 mW switching powers.
The authors report on low-density InAs quantum dots (QDs) grown on AlGaInAs surfaces lattice matched to InP using post-growth annealing by solid-source molecular beam epitaxy. Clearly spatially separated QDs with a dot density of about 5 × 10{sup 8} cm{sup −2} are obtained by using a special capping technique after the dot formation process. High-resolution micro-photoluminescence performed on optimized QD structures grown on distributed Bragg reflector exhibits single QD emissions around 1.5 μm with narrow excitonic linewidth below 50 μeV, which can be used as single photon source in the telecom wavelength range.