Near-infrared Quantum Efficiency Research Articles

A High-Performance 2.5 μm Charge Domain Global Shutter Pixel and Near Infrared Enhancement with Light Pipe Technology.

We developed a new 2.5 μm global shutter (GS) pixel using a 65 nm process with an advanced light pipe (LP) structure. This is the world’s smallest charge domain GS pixel reported so far. This new developed pixel platform is a key enabler for ultra-high resolution sensors, industrial cameras with wide aperture lenses, and low form factors optical modules for mobile applications. The 2.5 μm GS pixel showed excellent optical performances: 68% quantum efficiency (QE) at 530 nm, ±12.5 degrees angular response (AR), and quite low parasitic light sensitivity (PLS)—10,400 1/PLS with the F#2.8 lens. In addition, we achieved an extremely low memory node (MN) dark current 13 e−/s at 60 °C by fully pinned MN. Furthermore, we studied how the LP technology contributes to the improvement of the modulation transfer function (MTF) in near infrared (NIR) enhanced GS pixel. The 2.8 μm GS pixel using a p-substrate showed 109 lp/mm MTF@50% at 940 nm, which is 1.6 times better than that without an LP. The MTF can be more enhanced by the combination of the LP and the deep photodiode (PD) electrically isolated from the substrate. We demonstrated the advantage of using LP technology and our advanced stacked deep photodiode (SDP) technology together. This unique combination showed an improvement of more than 100% in NIR QE while maintaining an MTF that is close to the theoretical Nyquist limit (MTF @50% = 156 lp/mm).

Cooperative downconversion and near-infrared luminescence of Tb3+/Yb3+ co-doped tellurite glass

Abstract The different concentration of Tb3+/Yb3+ co-doped tellurite glasses were prepared by high-temperature melting–quenching method. The near-infrared (NIR) luminescence of co-doped samples upon the excitation of Tb3+ ions with a green visible photon at 484 nm was investigated, and two NIR photons could be emitted by Yb3+ (2F5/2 → 2F7/2) through cooperative energy transfer from Tb3+ to two Yb3+ ions. On the other hand, the Yb3+ co-doped concentration dependence on the visible and NIR emissions, decay lifetimes and quantum efficiencies from the downconversion have been studied. The NIR quantum efficiency achieved 172% before the concentration quenching threshold.

The Time Response of Exponential Doping NEA InGaAs Photocathode Applied to near Infrared Streak Cameras

An exponential doping NEA InGaAs photocathode is theoretically proposed to apply in the near infrared streak camera. The photocathode time response is calculated and analyzed by using a photoelectron non-steady method. The numerical results show that the excited electrons in the InGaAs active layer is accelerated due to the built-in electric field induced by the exponential doping structure, which shortens the transport time of minority carriers in the photocathode and thus, the time response is greatly improved. In addition, the exponential doping InGaAs photocathode possesses time response of less than 10 picoseconds and near-infrared quantum efficiency of 10%.

Near-infrared quantum efficiency of uncooled photodetectors based on InGaAs/GaAsSb quantum wells lattice-matched to InP

The near-infrared quantum efficiency of pin photodetectors based on a lattice-matched type-II InGaAs/GaAsSb absorption region has been measured. The quantum efficiencies for these devices are 80.2 and 57.8% at 1064 and 1550%nm, respectively. These results are comparable to the more commonly-used InGaAs/InP photodetectors.

Efficient near-infrared down conversion in Zn2SiO4:Tb3+,Yb3+ thin-films

We demonstrate a facile approach for the synthesis of Zn2SiO4:Tb3+,Yb3+ transparent thin films. The thin film phosphor was characterized by various methods including x-ray diffraction, atom force microscope, and photoluminescence studies. Upon excitation with a UV-blue photon in the range of 350–485 nm, an intense near-infrared (NIR) emission at around 900–1100 nm has been obtained, which is assigned to the electronic transition F27/2→F25/2 of Yb3+ upon exploring the cooperative down conversion mechanism from Tb3+ to Yb3+. The dependence of Yb3+ doping concentration on the visible- and NIR-emissions, decay lifetime, and quantum efficiencies of the thin-films has been investigated. The optimal internal NIR quantum efficiency could be as high as 154.1%.

Concentration-dependent near-infrared quantum cutting in GdBO3:Tb3+,Yb3+ nanophosphors

An efficient near-infrared (NIR) quantum-cutting (QC), involving the emission of two low-energy NIR photons from an absorbed visible photon via a cooperative downconversion mechanism in GdBO3:Tb3+,Yb3+ nanophosphors, has been demonstrated. Upon excitation of Tb3+ with a visible photon at 486nm, two NIR photons could be emitted by Yb3+ through cooperative energy transfer from Tb3+ to two Yb3+ ions. The dependence of Yb3+ doping concentration on the visible and NIR emissions, decay lifetime, and quantum efficiencies from the QC phosphors has been investigated. Calculations indicate that the optimal NIR quantum efficiency approaches 182% before reaching concentration quenching threshold. Application of the QC nanophosphors in silicon-based solar cells might greatly enhance its response.

Evaluation of the OH− influence on visible and near-infrared quantum efficiencies of Tm3+ and Yb3+ codoped sodium aluminophoshate glasses

This paper presents a throughout spectroscopic investigation of Yb3+∕Tm3+ codoped sodium aluminophosphate glasses in the visible and near-infrared spectral regions. Two sets of samples, prepared in air and nitrogen atmospheres, were characterized by transmission, absorption, luminescence, excited state lifetimes, and upconversion. The data are discussed in terms of OH− contents in the samples, and their influence on Tm3+ fluorescence quantum efficiencies. Besides, a theoretical analysis of radiative properties, by the Judd-Ofelt [Phys. Rev. 127, 750 (1962)]; J. Chem. Phys. 37, 511 (1962)] theory, is also presented in comparison to experimental data. Results indicate that samples prepared in N2 atmosphere, with lower OH− content, present superior properties than those prepared in air. Among these properties are a 30% more extensive infrared transmission of the host matrix, higher emission intensities, and decreased quenching effects, characterizing them as potential materials for high power laser generation, as well as efficient upconversion.

Near infrared detection by means of coordination complexes

We report on the detection of near infrared (NIR) radiation in the range 900–1600 nm by means of coordination complexes such as [M(R tR’timdt) 2] x− (M = Ni, Pd, Pt; R,R’timdt = formally monoreduced disubstituted imidazolidine-2,4,5-trithione; x = 0, 1), and [{Ru(bipy) 2} 2(μ-L)] x+ (H 3L = 9-phenyl-2,3,7-trihydroxy-6-fluorone; x = 1, 3). By exploiting these stable coordination complexes absorbing in the visible and NIR region, the poor stability to air and light usually found in low band-gap organic semiconductors can be overcome. [M(R,R’timdt) 2] and [{Ru(bipy) 2} 2(μ-L)] 1+ complexes show π-π* transitions in the range 700-1000 nm, which can be bathochromically shifted by changing their oxidation state. Taking profit of this feature, we prepared photodetecting devices operating in the NIR region up to 1600 nm, thus reaching the appealing spectral range of telecommunications. NIR quantum efficiencies of these preliminary photodetectors, made by simple casting from solution, are comparable to those in the visible of most devices based on pristine organic materials. We succeeded in detecting train pulses with a repetition frequency of about 200 kHz at 960 nm and 80 kHz at 1450 nm, to our knowledge an unprecedented result that demonstrates the possibility to enter the NIR region by organic molecular-based devices.

A Linear Charge-Coupled Device Detector System for Spectroscopy

The spectroscopically important performance capabilities of a linear charge-coupled device detector system, along with the methods used to evaluate the detector performance, are described. The linearity, read noise, full-well capacity, charge transfer efficiency, and ultraviolet to near-infrared quantum efficiency of the detector are presented along with the methods required to operate the detector in unconventional modes allowing low noise and antiblooming operation. With the antiblooming mode of operation, the detector performance is shown to be unaffected by light overloads hundreds of times over the saturation level. The performance of the detector for high-resolution diagnostic studies of hollow cathode lamps as well as for molecular fluorescence is presented.