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In the present article, we propose a monolithically integrated Michelson interferometer using a λ = 4 µm InGaAs/InAlAs quantum cascade laser as the light source. By using simple fringe detection and a four-point interpolation on each fringe, we will be able to detect minimal object displacements of 500 nm—corresponding to 25% of half the laser emission wavelength. Such an interferometric photonic integrated circuit has interesting applications for precision computerized numerical controlled machines. Since the industrial standard of such machines currently consists of glass-based linear encoders with a resolution of 5 µm, our interferometer-based system will enable an improvement of at least one order of magnitude. [ABSTRACT FROM AUTHOR]

Gallium ion (Ga+) beam damage induced indium (In) precipitation in indium gallium arsenide (InGaAs)/indium aluminium arsenide (InAlAs) multiple quantum wells and its corresponding evolution under electron beam irradiation was investigated by valence electron energy loss spectroscopy (VEELS) and high‐angle annular dark‐field imaging (HAADF) in scanning transmission electron microscopy (STEM). Compared with argon ion milling for sample preparation, the heavier projectiles of Ga+ ions pose a risk to trigger In formation in the form of tiny metallic In clusters. These are shown to be sensitive to electron irradiation and can increase in number and size under the electron beam, deteriorating the structure. Our finding reveals the potential risk of formation of In clusters during focused ion beam (FIB) preparation of InGaAs/InAlAs quantum well samples and their subsequent growth under STEM‐HAADF imaging, where initially invisible In clusters of a few atoms can move and swell during electron beam exposure. LAY DESCRIPTION: In this paper, the evolution of Ga+ implantation induced In precipitation in InGaAs/InAlAs multiple quantum wells under electron beam irradiation was investigated by valence electron energy loss spectroscopy (VEELs), energy dispersive X‐ray spectroscopy (EDXs) and high‐angle annular dark‐field (HAADF) imaging technique based in a probe aberration corrected scanning transmission electron microscope. In contrast to Ar+ ion bombardment, the projectile of focused Ga+ ions is able to trigger the clustering of In interstitials in InGaAs/InAlAs multiple quantum wells, which allows the formation of metallic In precipitates. Afterwards, by exploiting an extensive electron beam rastering on the region of In precipitation, the increase of electron irradiation time could lead to a pronounced swelling of In cluster size. Especially for the region contains In precipitates of several atoms, where the morphology of In cluster is invisible in atomic image. The continuous electron irradiation could give rise to the promotion of In clustering, allowing the structure of In precipitates been resolved by HAADF image. Our finding reveals the potential risk of formation of In precipitates during focused Ga+ ion beam bombarded InGaAs/InAlAs semiconductors and the subsequent evolution of In clustering under electron beam rastering. These findings emphasise the need for caution when studying FIB prepared In‐based III–V quantum well specimens using TEM even in the In(Ga,Al)As system, as the initially formed In‐rich clusters are so small they can remain invisible for some time. [ABSTRACT FROM AUTHOR]

In the present article, we propose a monolithically integrated Michelson interferometer using a λ = 4 µm InGaAs/InAlAs quantum cascade laser as the light source. By using simple fringe detection and a four-point interpolation on each fringe, we will be able to detect minimal object displacements of 500 nm—corresponding to 25% of half the laser emission wavelength. Such an interferometric photonic integrated circuit has interesting applications for precision computerized numerical controlled machines. Since the industrial standard of such machines currently consists of glass-based linear encoders with a resolution of 5 µm, our interferometer-based system will enable an improvement of at least one order of magnitude.

To give consideration to both chip density and device performance, an In0.53Ga0.47As vertical electron–hole bilayer tunnel field effect transistor (EHBTFET) with a P+-pocket and an In0.52Al0.48As-block (VPB-EHBTFET) is introduced and systematically studied by TCAD simulation. The introduction of the P+-pocket can reduce the line tunneling distance, thereby enhancing the on-state current. This can also effectively address the challenge of forming a hole inversion layer in an undoped InGaAs channel during device fabrication. Moreover, the point tunneling can be significantly suppressed by the In0.52Al0.48As-block, resulting in a substantial decrease in the off-state current. By optimizing the width and doping concentration of the P+-pocket as well as the length and width of the In0.52Al0.48As-block, VPB-EHBTFET can obtain an off-state current of 1.83 × 10−19 A/μm, on-state current of 1.04 × 10−4 A/μm, and an average subthreshold swing of 5.5 mV/dec. Compared with traditional InGaAs vertical EHBTFET, the proposed VPB-EHBTFET has a three orders of magnitude decrease in the off-state current, about six times increase in the on-state current, 81.8% reduction in the average subthreshold swing, and stronger inhibitory ability on the drain-induced barrier-lowering effect (7.5 mV/V); these benefits enhance the practical application of EHBTFETs. [ABSTRACT FROM AUTHOR]

To give consideration to both chip density and device performance, an In0.53Ga0.47As vertical electron–hole bilayer tunnel field effect transistor (EHBTFET) with a P+-pocket and an In0.52Al0.48As-block (VPB-EHBTFET) is introduced and systematically studied by TCAD simulation. The introduction of the P+-pocket can reduce the line tunneling distance, thereby enhancing the on-state current. This can also effectively address the challenge of forming a hole inversion layer in an undoped InGaAs channel during device fabrication. Moreover, the point tunneling can be significantly suppressed by the In0.52Al0.48As-block, resulting in a substantial decrease in the off-state current. By optimizing the width and doping concentration of the P+-pocket as well as the length and width of the In0.52Al0.48As-block, VPB-EHBTFET can obtain an off-state current of 1.83 × 10−19 A/μm, on-state current of 1.04 × 10−4 A/μm, and an average subthreshold swing of 5.5 mV/dec. Compared with traditional InGaAs vertical EHBTFET, the proposed VPB-EHBTFET has a three orders of magnitude decrease in the off-state current, about six times increase in the on-state current, 81.8% reduction in the average subthreshold swing, and stronger inhibitory ability on the drain-induced barrier-lowering effect (7.5 mV/V); these benefits enhance the practical application of EHBTFETs.

AbstractWe calculated the correlation between the doping concentration of the charge layer and the multiplication layer for separate absorption, grading, charge, and multiplication InGaAs/InAlAs avalanche photodiodes (APDs). For this purpose, a predictable program was developed according to the concentration and thickness of the charge layer and the multiplication layer. We also optimized the design, fabrication, and characteristics of an APD for 20 Gbps application. The punch‐through voltage and breakdown voltage of the fabricated device were 10 V and 33 V, respectively, and it was confirmed that these almost matched the designed values. The 3‐dB bandwidth of the APD was 10.4 GHz, and the bit rate was approximately 20.8 Gbps.

—We constructed a model for a 3-stage InGaAs/InAlAs avalanche photodiode using numerical simulations based on the gain-noise mechanism. The contact layer, barrier layer, charge layer and multiplication layer of this model are optimized accordingly. The performance of the device can be improved by optimizing the thickness and doping concentration of the contact layer, increasing the thickness of the charge layer, and adding a barrier layer. At the same time, the addition of double heterojunction structure makes the performance of the device better, which enables a higher impact ionization rate of the multiplication layer. According to DSMT theory calculation results, the optimized 3-gain-stage device's gain is 90, and the excess noise factor is about 3.1. Compared with the 10-stage avalanche photodiode (with an excess noise factor of 5) studied at the same gain, this work shows higher performance at the lower stage. The optimized structure can provide design and optimization ideas for more stages of avalanche photodiode to increase gain and reduce excess noise. [ABSTRACT FROM AUTHOR]

A $15~\mu \text{m}$ pitch extended wavelength In0.83Ga0.17As/ InP mega-pixel focal plane array (FPA) with a format of 1280 $\times 1024$ and a spectral response range of 1150–2450 nm has been demonstrated for the first time. High fill factor up to >86%, low dark current densities down to < 133 nA/cm2, high quantum efficiencies up to >69%, were achieved by implementing novel high density micro-mesa array processing technologies. A proprietary wafer bowing control technique was developed, attaining a high pixel operability of 99.37%. Laboratory imaging was also demonstrated, showing potentiality for high resolution imaging applications in a wider SWIR spectrum range. [ABSTRACT FROM AUTHOR]

We calculated the correlation between the doping concentration of the charge layer and the multiplication layer for separate absorption, grading, charge, and multiplication InGaAs/InAlAs avalanche photodiodes (APDs). For this purpose, a predictable program was developed according to the concentration and thickness of the charge layer and the multiplication layer. We also optimized the design, fabrication, and characteristics of an APD for 20 Gbps application. The punch‐through voltage and breakdown voltage of the fabricated device were 10 V and 33 V, respectively, and it was confirmed that these almost matched the designed values. The 3‐dB bandwidth of the APD was 10.4 GHz, and the bit rate was approximately 20.8 Gbps. [ABSTRACT FROM AUTHOR]

A highly sensitive terahertz (THz) detector based on a photoconductive antenna (PCA) with plasmonic amplification on the basis of an InGaAs/InAlAs superlattice heterostructure is proposed. A noticeable increase in the photocurrent recorded by a plasmonic PCA detector and the signal-to-noise ratio was experimentally detected compared to the same parameters for the PCA detector without plasmonic electrodes. The efficiency of plasmonic electrodes has been experimentally confirmed by pulsed THz spectroscopy by measuring the dependence of the detector's THz signal amplitude on the polarization of the incident pump laser radiation. [ABSTRACT FROM AUTHOR]

An optimized empirical modelling for a 0.25µm gate length of highly strained channel of an InP-based pseudomorphic high electron mobility transistor (pHEMT) using InGaAs-InAlAs material systems is presented. An accurate procedure for extraction is described and tested using the pHEMT measured dataset of I-V characteristics and related multi-bias s-parameters over 20GHz frequency range. The extraction of linear and nonlinear parameters from the small signal and large signal pHEMT equivalent model are performed in ADS. The optimized DC and S-parameter model for the pHEMT device provides a basis for active device selection in the MMIC low noise amplifier circuit designs. [ABSTRACT FROM AUTHOR]

In $$_{x}$$ Ga $$_{1-{x}}$$ As/In $$_{y}$$ Al $$_{1-{y}}$$ As HEMT structures $${\updelta }$$ -doped by Si were grown by molecular beam epitaxy on InP substrate. We investigated the influence of the In content on the electron mobilities and effective masses in dimensionally quantized subbands. The electron effective masses were determined by the temperature dependence of the amplitude of the Shubnikov-de Haas effect at 1.6 and 4.2 K. We found that the more the In content in quantum well (QW), the less the electron effective masses. The mobilities are higher in HEMT structures with wider and deeper QW. The energy band diagrams were calculated by using Vegard's law for basic parameters. The calculated band diagrams are in a good agreement with the experimental data of photoluminescence spectra. [ABSTRACT FROM AUTHOR]