The NSF NeXUS user facility is designed to enable direct observation of electron motion with attosecond femtosecond time resolution, angstrom spatial and element-specific spectral resolution. will level the scientific playing field by providing researchers across disciplines access most advanced characterization tools available worldwide for studying ultrafast dynamics in molecules materials.

High sensitivity avalanche photodiodes (APDs) operating at eye-safe infrared wavelengths (1400–1650 nm) are essential components in many communications and sensing systems. We report the demonstration of a room temperature, ultrahigh gain ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>M</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>278</mml:mn> </mml:mrow> </mml:math> , <mml:mi>λ</mml:mi> <mml:mn>1550</mml:mn> <mml:mspace...

We report the gain, noise, and dark current characteristics of random alloy Al0.79In0.21As0.74Sb0.26 (hereafter AlInAsSb)-based avalanche photodiodes (APDs) on InP substrates. observe, at room temperature, a low excess noise corresponding to k value (ratio impact ionization coefficients) 0.018 density 82 μA/cm2 with gain 15. These performance metrics represent an order magnitude improvement k-value over commercially available APDs InAlAs multiplication layers grown This material is also...

We report on the demonstration of Al0.85Ga0.15As0.56Sb0.44 (hereafter, AlGaAsSb) avalanche photodiodes (APDs) with a 1000 nm-thick multiplication layer. Such thick AlGaAsSb device was grown by digital alloy technique to avoid phase separation. The current-voltage measurements under dark and illumination conditions were performed determine gain for APDs. highest ∼ 42, initiation occurred at 21.6 V. breakdown voltage found be around −53 measured current densities bulk surface components 6.0...

We demonstrate low noise random alloy (RA) Al0.85Ga0.15AsSb (hereafter AlGaAsSb) avalanche photodiodes (APDs) nearly lattice-matched to InP substrates. In contrast digital (DA), RAs are manufacturable due the ease of growth. The 910 nm-thick RA AlGaAsSb was grown at a temperature around 450 °C mitigate phase separation by suppressing surface mobility adatoms. high quality material verified x-ray diffraction, Nomarski, and atomic force microscope images. Capacitance–voltage measurement found...

Digital alloy and random Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.85</sub> Ga xmlns:xlink="http://www.w3.org/1999/xlink">0.15</sub> As xmlns:xlink="http://www.w3.org/1999/xlink">0.56</sub> Sb xmlns:xlink="http://www.w3.org/1999/xlink">0.44</sub> avalanche photodiodes (APDs) exhibit low excess noise, comparable to Si APDs. Consequently, this material is a promising multiplication layer candidate for separate absorption, charge,...

Dark current is considered as one of the important parameters to suppress temporal noise and enhance sensitivity photodetectors. This study shows effect active layer thickness different interfacial layers in suppression leakage current. High-sensitivity (D* &amp;gt; 1012 Jones) perovskite photodetectors (PPDs) are fabricated using device structure ITO/PEDOT: PSS/FA0.95Cs0.05PbI3 (dPVSK)/ electron transport (ETL)/BCP/Ag with &amp;lt;1 pA Hz−½. These PPDs have a broadband response from...

High-sensitivity avalanche photodiodes (APDs) are used to amplify weak optical signals in a wide range of applications, including telecommunications, data centers, spectroscopy, imaging, light detection and ranging, medical diagnostics, quantum applications. This paper reports antimony-based separate absorption, charge, multiplication structure APDs on InP substrates. Al0.7In0.3As0.79Sb0.21 is for the multiplier region, InGaAs as absorber. The excess noise comparable that silicon APDs;...

We report the multiplication properties of Al0.85Ga0.15As0.07Sb0.93 for use in separate absorption charge and avalanche photodiode lattice matched to a GaSb substrate. The demonstration high gain, low excess noise multiplier is critical step toward performance photodiodes operating at wavelengths exceeding 2 μm. have measured impact ionization coefficients random alloy grown on substrates from 210 421 kV/cm. Our results show an α value (0.25–40×103 cm−1) significantly greater than β...

The first optical spectroscopic investigation of MoC has revealed a complicated vibronic spectrum consisting about 35 bands between 17 700 and 24 000 cm−1. Analysis shown the ground state to be Ω=0+ spinorbit component Σ3− that derives from 10σ211σ25π42δ2 configuration. X 3Σ0+− rotational constant for Mo9812C was determined B0=0.553 640±0.000 055 cm−1, giving r0=1.687 719±0.000 084 Å. Consideration spin-uncoupling effects in 3Σ− requires this value revised r0=1.6760 Å, which represents our...

Digital alloy Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.85</sub> Ga xmlns:xlink="http://www.w3.org/1999/xlink">0.15</sub> As xmlns:xlink="http://www.w3.org/1999/xlink">0.56</sub> Sb xmlns:xlink="http://www.w3.org/1999/xlink">0.44</sub> , random and xmlns:xlink="http://www.w3.org/1999/xlink">0.79</sub> In xmlns:xlink="http://www.w3.org/1999/xlink">0.21</sub> xmlns:xlink="http://www.w3.org/1999/xlink">0.74</sub>...

The rising concentration of greenhouse gases, especially methane and carbon dioxide, is driving global temperature increases exacerbating the climate crisis. Monitoring these gases requires detectors that operate in extended short-wavelength infrared range (~2.4 µm), covering (1.65 µm) dioxide (2.05 wavelengths. Here, we present a high-performance linear mode avalanche photodetector (APD) with an InGaAs/GaAsSb type-II superlattice absorber AlGaAsSb multiplier, matched to InP substrates. This...

We investigate carrier localization in the InAs/AlSb type-II superlattice (T2SL) material system using temperature- and excitation power (Iex)-dependent photoluminescence (PL). Evidence of T2SLs was observed by an S-shaped temperature dependence PL peak position. Analysis Iex-dependent at various temperatures also shows existence T2SLs. The thermal activation energies were extracted to identify nonradiative recombination mechanisms possible origins localized states. found that there are two...

Abstract We report on engineering impact ionization characteristics of In 0.53 Ga 0.47 As/Al 0.48 0.52 As superlattice avalanche photodiodes (InGaAs/AlInAs SL APDs) InP substrate to design and demonstrate an APD with low k -value. InGaAs/AlInAs APDs three different periods (4 ML, 6 8 ML) achieve the same composition as Al 0.4 0.07 quaternary random alloy (RA). The simulated results RA SLs predict that have lower -values than because electrons can readily reach their threshold energy for...

For short-wavelength infrared (SWIR) avalanche photodiodes, a separate absorption, charge, and multiplication design is widely used. AlInAsSb on an InP substrate potential layer with lattice match to absorber candidates across the SWIR. Our new measurements demonstrate that promising multiplier candidate relatively low dark current density of 10−4 A/cm2 at gain 30; high gain, measured up 245 in this study; large differentiation electron hole ionization leading excess noise, be 2.5 30. These...

We provide an overview of our progress on the development linear mode avalanche photodiodes (LmAPDs) InP substrates using antimony (Sb)-based multipliers for short-wavelength infrared (SWIR) spectral region. identify key figures merit LmAPDs to higher sensitivity and speed applications like light detection ranging (LiDAR) remote sensing. discuss design separate absorption, charge, multiplication (SACM) APDs that are used narrow gap absorption. summarize results impact ionization, gain, dark...

We present an optical spectroscopy analysis of the molecular beam epitaxy-grown InAs/GaSb quantum systems to study higher-order transitions in superlattices (SLs). have investigated two type-II SL structures with different layer widths: $\mathrm{In}{\mathrm{As}}_{8\mathrm{ML}}/\mathrm{Ga}{\mathrm{Sb}}_{8\mathrm{ML}}$ and $\mathrm{In}{\mathrm{As}}_{10\mathrm{ML}}/\mathrm{Ga}{\mathrm{Sb}}_{10\mathrm{ML}}$. To experimentally determine spectral distribution transitions, Fourier-transformed...

The performance of the photodetector is often primary limiting factor affecting a free space communication or LiDAR system's sensitivity. Avalanche photodiodes (APDs) can be used to improve signal noise ratio (SNR) compared conventional <i>p-i-n</i> photodiodes. Our study focuses on demonstrating an APD operating in eye-safe short-wave infrared (SWIR) spectrum (&gt;1400 nm) with high multiplication (<i>M</i>&gt;1200) and low excess (<i>F</i>&lt;7 at <i>M</i>=200) room temperature. This...

Digital alloy Al0.85Ga0.15As0.56Sb0.44 and random Al0.79In0.21As0.74Sb0.26 avalanche photodiodes with a 1-μm multiplication layer exhibit low excess noise under 543-nm laser illumination comparable to Si photodiodes. This has motivated study of the optical characteristics these materials. The absorption coefficients complex refractive indices were extracted via variable-angle spectroscopic ellipsometry. Features three semiconductor fitting approaches are compared, Kramers–Kronig-consistent...

We theoretically and experimentally investigate the application of an open-circuit voltage photodetector (VocP) architecture for mid-wave infrared (MWIR, 3–5 μm) detection imaging. In contrast to conventional reverse-bias (RB) operation diode, which generates a photocurrent that is proportional photon irradiance, we evaluate potential using unbiased diodes generate voltage, VOC, under illumination. The predicted Noise Equivalent Differential Temperature (NEDT) VocP inferior RB when assume...

We have measured the helium induced pressure broadening and shifting of distinct hyperfine components j = 1 <-- 0 2 transitions HC14N at temperatures between 1.3 20 K. The HCN molecules were cooled to these using collisional cooling technique. As a test this technique we Doppler contribution spectral lines, measurements confirm that are same temperature as walls spectroscopic cell. observed transition coefficients differ from one another by much 5%. differences in reasonable agreement with...

Antenna coupled detectors break the intrinsic tradeoff between signal and noise by "collecting over a large area" "detecting small area". Most antenna in infrared rely on metal resonator structure. However, there are losses associated with metallic structures. We have demonstrated novel long-wave (LWIR) detector that combines dielectric an antimonide-based absorber. The consists of 3D, subwavelength InAsSb absorber embedded resonant, cylindrical made amorphous silicon. This architecture...

We present a method of determining the background doping type in semiconductors using capacitance–voltage measurements on overetched double mesa p–i–n or n–i–p structures. Unlike Hall measurements, this is not limited by conductivity substrate. By measuring capacitance devices with varying top and bottom sizes, we were able to conclusively determine which contained p–n junction, revealing polarity intrinsic layer. This method, when demonstrated GaSb structures, concluded that material...

We report the noise characteristics of an AlInAsSb avalanche photodiode (APD) on InP substrate. observe low excess corresponding to impact ionization coefficient ratio (k) 0.012, and a dark current density 55 μA/cm2 at gain 10 room temperature. The performance commercial APDs substrates is limited by state art (SOA) current. combination leads significant improvement compared provides potential candidate for noise, SOA, near-infrared applications. When combined in separate absorber, charge...