We report high-temperature (240–300K) operation of a tunneling quantum-dot infrared photodetector. The device displays two-color characteristics with photoresponse peaks at ∼6μm and 17μm. extremely low dark current density 1.55A∕cm2 300K for 1V bias is made possible by the tunnel filter. For 17μm absorption, measured peak responsivity 0.16A∕W (300K) 2V specific detectivity D* 1.5×107cmHz1∕2∕W (280K) 1V. Excellent performance are also 6μm photoresponse.

We have optimized the growth of multiple (40-70) layers self-organized InAs quantum dots separated by GaAs barrier in order to enhance absorption quantum-dot infrared photodetectors (QDIPs). In devices with 70 layers, at relatively large operating biases (/spl les/-1.0 V), dark current density is as low 10/sup -5/ A/cm/sup 2/ and peak responsivity ranges from /spl sim/0.1 0.3 A/W for temperatures T=150 K-175 K. The detectivity corresponding these currents high responsivities varies range...

Quantum-dot infrared photodetectors (QDIPs) are being studied extensively for mid-wavelength and long-wavelength detection because they offer normal-incidence, high-temperature, multispectral operation. Intersubband absorption, carrier lifetime, gain parameters that need to be better characterized, understood, controlled in order realize high-performance QDIPs. An eight-band k/spl middot/p model is used calculate polarization-dependent intersubband absorption. The calculated trend absorption...

Quantum dot infrared photodetectors (QDIPs) have emerged as attractive devices for sensing long wavelength radiation.Their principle of operation is based on intersublevel transitions in quantum dots (QDs).Three-dimensional confinement offers the advantages normal incidence operation, low dark currents and high-temperature operation.The performance characteristics mid-infrared with three kinds novel heterostructures active region are described here.These a device upto 70 QD layers,...

We report on the design and performance of multi-stack InAs/InGaAs sub-monolayer (SML) quantum dots (QD) based infrared photodetectors (SML-QDIP). SML-QDIPs are grown with number stacks varied from 2 to 6. From detailed radiometric characterization, it is determined that sample 4 SML has best performance. The s-to-p (s/p) polarized spectral response ratio this device measured be 21.7%, which significantly higher than conventional Stranski-Krastanov (∼13%) wells (∼2.8%). This result makes...

Mercury is highly toxic to human health in all of its oxidation states. Thus, developing a low cost, efficient metal ion sensor for the detection mercury ions at concentration levels down parts-per-billion (ppb) remains challenge. In present work, we have developed silver nanoparticles (Ag-NPs) impregnated poly(vinyle alcohol) capped 4-nitrophenylanthranilate (PVA-NPA) complex detection. The fluorescence intensity synthesized PVA-NPA found be quenched by Ag-NPs through dynamic quenching....

Wide energy gap inorganic halide perovskites have become emerging candidates for potential applications in modern optoelectronics devices. However, to date, these semiconducting compounds not been explored theoretically a significant extent. Herein, we performed ab initio computations explain the structural, electronic and optical behaviour of CsPbCl3 Mn-doped nanocrystals (NCs). We also synthesized NCs further validated our experimental results with density functional theory (DFT)...

A novel device-resonant tunneling quantum-dot infrared photodetector-has been investigated theoretically and experimentally. In this device, the transport of dark current photocurrent are separated by incorporation a double barrier resonant tunnel heterostructure with each layer device. The devices In/sub 0.4/Ga/sub 0.6/As-GaAs quantum dots grown molecular beam epitaxy. We have characterized designed for /spl sim/6 mu/m response, also exhibit strong photoresponse peak at sim/17 300 K due to...

The magnetic and structural properties of InAs:Mn self-organized diluted quantum dots grown by low-temperature (∼270°C), solid-source molecular-beam epitaxy using a very low InAs growth rate (<0.1ML∕s) are investigated. A Curie temperature (TC) ∼350K is measured in sample with Mn∕In flux ratio 0.15. Electron energy-loss spectroscopy confirms that most the Mn remains within dots. We propose as possible explanation for this high TC effects disorder introduced random incorporation...

A model for the dark current in quantum dot infrared photodetectors, including thermionic emission and field-assisted tunneling, is developed. The calculated currents are excellent agreement with measured values a wide range of temperatures (78 K-295 K) applied bias (0-3 V).

A high-performance InGaAs/GaAs vertical quantum dot infrared photodetector (QDIP) with combined barrier of quaternary In0.21Al0.21Ga0.58As and GaAs was investigated in this study. dominant long wavelength (∼10.2 μm) response observed from the device. The device demonstrates large responsivity (2.16 A/W) narrow spectral-width (Δλ/λ ∼0.14) high detectivity (1.01 × 1011 cm Hz1/2/W at 0.3 V) 10.2 μm 77 K. In addition, has also produced a order 6.4 1010 100 K bias 0.2 V, indicating its...

We have investigated optical properties and device performance of sub-monolayer quantum dots infrared photodetector with confinement enhancing (CE) barrier compared conventional Stranski-Krastanov a similar design. This dots-in-a-well structure CE enables higher increased absorption efficiency due to stronger overlap wavefunctions between the ground state excited state. Normal incidence photoresponse peak is obtained at 7.5 μm detectivity 1.2 × 1011 cm Hz1/2 W−1 responsivity 0.5 A/W (77 K,...

An InAs/GaAs quantum dot infrared photodetector with strong, multicolor, broadband (5–20 μm) photoresponse is reported. Using a combined quaternary In0.21Al0.21Ga0.58As and GaAs capping that relieves strain maintains strong carrier confinement, we demonstrate four color response peaks in the midwave- (5.7 μm), longwave- (9.0 14.5 far- (17 regions. Narrow spectral widths (7% to 9%) are noted at each of these wavelengths including responsivity value ∼95.3 mA/W μm. field multi-band k⋅p theory,...

A three-color quantum-dot infrared photodetector has been fabricated and characterized. The active absorption region consists of undoped In/sub 0.4/Ga/sub 0.6/As quantum dots separated by GaAs barriers. Intersublevel transitions electrons in the results peaks at /spl sim/3.5, 7.5, 22 μm. devices were characterized 80 K 120 K. dark current density is 10/sup -6/ A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for an applied bias 1 V....

We present a model for the effect of thermal annealing on single-layer InAs/GaAs quantum dot (QD) heterostructure and study corresponding variation in full photoluminescence (PL) spectrum. In/Ga interdiffusion due to is modeled by Fickian diffusion Schrödinger equation solved separately electrons holes obtain ground state PL peaks at different temperatures. theoretically examine decrease strain effects carrier confinement potentials with annealing. spectra entire ensemble QDs, annealed...

We report the design, fabrication, and characterization of an electrically injected, spin-polarized, vertical-cavity surface-emitting laser. have demonstrated spin injection from ferromagnetic semiconductor (Ga,Mn)As into In0.2Ga0.8As∕GaAs quantum wells, transport across a distance ∼0.25μm for temperatures ranging 80to105K, detection through optical polarization measurements with coherent light emission. Controlled switching between right- left-elliptically polarized modes is achieved...

We demonstrate control of ZnO nanorod density for self-organized growth on buffer layers Si by varying Zn supersaturation during the initial phase, thereby altering competition between 2D and 1D modes. Higher favours nanorods diameter 1000, attributed to sharp facet edges, indicate that lower arrays have more uniform emission due a reduction in screening effects.