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Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers

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ABSTRACT

Potential barriers around quantum dots (QDs) play a key role in kinetics of photoelectrons. These barriers are always created, when electrons from dopants outside QDs fill the dots. Potential barriers suppress the capture processes of photoelectrons and increase the photoresponse. To directly investigate the effect of potential barriers on photoelectron kinetics, we fabricated several QD structures with different positions of dopants and various levels of doping. The potential barriers as a function of doping and dopant positions have been determined using nextnano3 software. We experimentally investigated the photoresponse to IR radiation as a function of the radiation frequency and voltage bias. We also measured the dark current in these QD structures. Our investigations show that the photoresponse increases ~30 times as the height of potential barriers changes from 30 to 130 meV.

No MeSH data available.


QDIP structures with n-type intra-QD layer doping (a) and inter-QD layer doping (b).
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Figure 1: QDIP structures with n-type intra-QD layer doping (a) and inter-QD layer doping (b).

Mentions: The doping for the active layers of the QDIPs can be done in several manners (see Table 1). The QDIP structures with two types of doping have been grown: intra-QD layer doping and inter-QD layer doping. Samples with intra-QD layer doping B44 and B52 have been grown with Si doping in the InAs dots (Figure 1a). The equivalent doping sheet concentration is 2.7 and 5.4 × 1011 cm-2 for B44 and B52, respectively. Samples with inter-QD layer doping B45, B53, and B54 have been grown with the Si doping directly in the middle of each AlGaAs barrier layer (Figure 1b). The thickness of doped layer is 6.4 nm. The doping sheet concentration is 2.7, 5.4, and 8.1 × 1011 cm-2 for B45, B53, and B54, respectively. Also, samples with inter-QD layer doping, B46, have been grown with the modulation doping. Each Si-doped 6.4-nm thick layer moves down 2.144 nm in AlGaAs barrier layer. Each repetition ends with 2.5, 4.644, 6.788, 8.932, 11.076, 13.22, 15.364, 17.508, 19.652, and 21.8 nm below AlGaAs barrier layer. The doping sheet concentration is 2.7 × 1011cm-2.


Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers
QDIP structures with n-type intra-QD layer doping (a) and inter-QD layer doping (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211266&req=5

Figure 1: QDIP structures with n-type intra-QD layer doping (a) and inter-QD layer doping (b).
Mentions: The doping for the active layers of the QDIPs can be done in several manners (see Table 1). The QDIP structures with two types of doping have been grown: intra-QD layer doping and inter-QD layer doping. Samples with intra-QD layer doping B44 and B52 have been grown with Si doping in the InAs dots (Figure 1a). The equivalent doping sheet concentration is 2.7 and 5.4 × 1011 cm-2 for B44 and B52, respectively. Samples with inter-QD layer doping B45, B53, and B54 have been grown with the Si doping directly in the middle of each AlGaAs barrier layer (Figure 1b). The thickness of doped layer is 6.4 nm. The doping sheet concentration is 2.7, 5.4, and 8.1 × 1011 cm-2 for B45, B53, and B54, respectively. Also, samples with inter-QD layer doping, B46, have been grown with the modulation doping. Each Si-doped 6.4-nm thick layer moves down 2.144 nm in AlGaAs barrier layer. Each repetition ends with 2.5, 4.644, 6.788, 8.932, 11.076, 13.22, 15.364, 17.508, 19.652, and 21.8 nm below AlGaAs barrier layer. The doping sheet concentration is 2.7 × 1011cm-2.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Potential barriers around quantum dots (QDs) play a key role in kinetics of photoelectrons. These barriers are always created, when electrons from dopants outside QDs fill the dots. Potential barriers suppress the capture processes of photoelectrons and increase the photoresponse. To directly investigate the effect of potential barriers on photoelectron kinetics, we fabricated several QD structures with different positions of dopants and various levels of doping. The potential barriers as a function of doping and dopant positions have been determined using nextnano3 software. We experimentally investigated the photoresponse to IR radiation as a function of the radiation frequency and voltage bias. We also measured the dark current in these QD structures. Our investigations show that the photoresponse increases ~30 times as the height of potential barriers changes from 30 to 130 meV.

No MeSH data available.