InAs/GaAs p-type quantum dot infrared photodetector with higher efficiency (original) (raw)
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Exceptionally Narrow-Band Quantum Dot Infrared Photodetector
IEEE Journal of Quantum Electronics, 2012
InGaAlAs/InGaAs/InGaAlAs/InAs/InP quantumdot structures have been investigated for the development of infrared photodetectors capable of generating photocurrent peaks exceptionally narrow for sharp wavelength discrimination. Our specially designed structure displays a photocurrent peak at 12 µm with a full width at half maximum, limited by inhomogeneous broadening, of only 4.5 meV. In agreement with two independent energy level calculations, we attribute this peak to photon absorption between InAs quantum dot bound states, followed by a three step carrier extraction mechanism in which the coupling to the adjacent InGaAs quantum well is a key feature. The possible role played by intraband Auger scattering, multiphoton sequential absorption and tunneling in generating the observed current peak is also addressed.
A Study on Doping Density in InAs/GaAs Quantum Dot Infrared Photodetector
Japanese Journal of Applied Physics, 2004
We study the influence of doping density and the resulting optimum operation voltage on the performance of quantum dot infrared photodetectors (QDIPs). The optimum operation voltage, where detectivity becomes maximum, becomes smaller as the doping density increases. This is because the optimum dark current levels are similar regardless of the doping density. We confirmed experimentally that the optimum dark current level is 5mA(currentdensity:5 mA (current density: 5mA(currentdensity:A/cm 2 ) for our samples. It is found that the higher doping density improves the performance in the range used in this experiment (5 Â 10 16 -5 Â 10 17 /cm 3 ). The response to a normal incident light is confirmed and the possibility of high-temperature operation of QDIP is shown.
This study reports the effect of doping level on the performance of InAs/GaAs quantum-dot infrared photodetectors (QDIPs). Two QDIP samples were prepared via molecular beam epitaxy: n +-i(QDs)-n + QDIP with undoped quantum dot (QD) active region, referred to as undoped QDIP, and n +-n(QDs)-n + QDIPs intended to contain two electrons per QDs, referred to as doped QDIP. InAs self-assembled QDs were grown on GaAs (001) wafers by three mono-layers of InAs deposition. Both QDIPs showed a photoluminescence peak at 1.182 µm as well as a similar broad photocurrent (PC) spectrum peaked at about 7.5 µm, ranging from 4 µm to 9 µm at 5 K. Undoped QDIP yielded a PC spectrum of up to 100 K, whereas doped QDIP had a PC spectrum of up to 40 K only. This finding was mainly attributed to the lower dark current properties of undoped QDIP. Undoped QDIP at 77 K showed five orders of magnitude lower than the dark current of doped QDIP at 5 K. His research interests are epitaxial growth of semiconductor nanostructures and their applications for optoelectronic devices such as quantum-well,-wire, and-dot infrared photodetectors.
Quantum dot infrared photodetectors in new material systems
Physica E-low-dimensional Systems & Nanostructures, 2000
Infrared detectors were implemented on InAs self-assembled quantum dots fabricated using Stranski-Krastanov growth mode on InAlAs matrix, lattice matched to InP (0 0 1) substrates. These dots grow with a shape of small elongated boxes, with their long axis along the [ 1 1 0] direction, and with a high concentration of 7 × 10 10 cm −2 . Photoconductive measurements were performed in all three polarizations. Rich spectra in the range of 50 -500 meV, with di erent polarization selection rules were observed. The bias dependence of peak intensity of the intraband transitions serves as an additional tool to identify their origin. Some of the peaks, which increase linearly with bias, are attributed to bound-to-continuum transitions. Others, which appear only at larger biases, and increase superlinearly, are due to bound-to-bound transitions. The magnitude of detector responsivity at normal-incidence is similar to that obtained for polarization normal to the layers, and is comparable to that achieved in QWIPs. BLIP conditions prevail at 77 K for integral photocurrent response at F#1. The e ect of unintentional doping is discussed. It is shown that this doping can be destructive for detector operation unless the density of dots is large. ?
IEEE Transactions on Nanotechnology, 2015
In this paper, we compare three design architectures for quantum dot infrared photodetectors-InGaAs-capped InAs dots, InAs dot-in-a-well (DWELL), and InAs submonolayer (SML) heterostructures-in terms of optical and spectral behavior. The photoluminescence (PL) intensity measured of the SML sample at 8 K was 20 times stronger than that of the other samples, and its full-width at half-maximum value broader than the rest. Activation energy was calculated using temperature-dependent PL and dark current measurements, which showed the same trend. Peak spectral responses for the InGaAs-capped InAs dot and DWELL samples were observed at 4.1 and 7.3 µm and at 4.1 and 8.5 µm, respectively; however, only a single transition was observed for the SML sample because of the absence of a wetting layer. Spectral response of DWELL sample exhibited bias tunability at 87 K, and the SML sample exhibited high temperature of operation till 110 K. One order increment in responsivity was observed in the SML sample compared to others. The peak detectivity of InGaAs-capped InAs dot, DWELL, and SML samples was 4.1 10 9 , 4.99 10 9 , and 3.89 10 9 Jones, respectively, at 87 K.
Thin Solid Films, 2014
The spectral and electrical properties of vertically coupled quaternary (InAlGaAs) capped InAs/GaAs quantum dot infrared photodetector with different capping thicknesses are investigated, and compared with a conventional quaternary capped uncoupled detector. Electronic coupling between quantum dot layers leads to a reduction in the ground state energy level and hence greater electronic confinement, which reduces the dark current and enhances the detectivity. These expectations are confirmed by our experimental results. Most significantly one order enhancement in peak detectivity (from 1.1 × 10 9 cm Hz 1/2 /W to 2.48 × 10 10 cm Hz 1/2 /W) is observed for optimized coupled quantum dot infrared photodetector compared to uncoupled device. The optimal interlayer barrier thickness which gives maximum detectivity is explained in terms of the interplay between electronic coupling and strain buildup in the heterostructure.