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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.


Normal incidence spectral photoresponse of samples B44–B46 at T = 80 K and bias voltage -5 V.
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Figure 3: Normal incidence spectral photoresponse of samples B44–B46 at T = 80 K and bias voltage -5 V.

Mentions: Normal incidence photoresponse spectra of the B44, B45, and B46 structures at T = 80 K and bias voltage -5 V are presented in Figure 3. We observed the maximum response at ~329 meV. Full width at half maximum is ~40 meV. Also, there is an additional small spike that can be clearly observed at the high-energy tail of the spectra. The energy corresponding to the spike is ~380 meV. The valley on the low-energy tail of the spectra at 300 meV corresponds to absorption of IR light by CO2 gas in the air. As seen from Figure 3, the photoresponse of B45 is several times larger then that for samples B44 and B46.


Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers
Normal incidence spectral photoresponse of samples B44–B46 at T = 80 K and bias voltage -5 V.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Normal incidence spectral photoresponse of samples B44–B46 at T = 80 K and bias voltage -5 V.
Mentions: Normal incidence photoresponse spectra of the B44, B45, and B46 structures at T = 80 K and bias voltage -5 V are presented in Figure 3. We observed the maximum response at ~329 meV. Full width at half maximum is ~40 meV. Also, there is an additional small spike that can be clearly observed at the high-energy tail of the spectra. The energy corresponding to the spike is ~380 meV. The valley on the low-energy tail of the spectra at 300 meV corresponds to absorption of IR light by CO2 gas in the air. As seen from Figure 3, the photoresponse of B45 is several times larger then that for samples B44 and B46.

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.