High electron mobility of β-HgS colloidal quantum dots with doubly occupied quantum states

Kim, Jaekyun; Yoon, Bitna; Kim, Jae Hyun; Choi, Young Shik; Kwon, Young Wan; Park, Sung Kyu; Jeong, Kwang Seob

doi:10.1039/c7ra07193k

Cited by 19 publications

(24 citation statements)

References 21 publications

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“…4,5 In the latter case, intraband transition appears in the mid-infrared when the material becomes degenerately doped. Mercury chalcogenides selfdoped nanocrystals especially HgS, [6][7][8] HgSe 9,10 and HgTe 11 are certainly the most investigated materials because of their ability to combine intraband absorption in the mid-infrared with photoconductive properties. In the following we will focus on HgSe CQDs as model system for self-doped nanocrystals.…”

Section: Introductionmentioning

confidence: 99%

Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals

et al. 2018

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Intraband and plasmonic transitions have appeared over the last years as an interesting tool to achieve optical absorption in the mid infrared. Tuning the doping magnitude has become a major challenge not only to tune the optical spectrum but also properties such as the dark current or the time response. Here we investigate the case of self-doped HgSe colloidal quantum dots (CQDs). Tuning of the doping was so far relying on band bending induced by a dipole design at the nanoparticle surface. With such a surface gating approach, it is difficult to conciliate both the massive tuning of the Fermi level with the preservation of transport properties of the CQD arrays. Here we propose a strategy to graft functionalized polyoxometalates (POMs) at the CQD surface and obtain simultaneously a massive tuning of the carrier density (≈5 electrons per nanoparticle) and conduction properties. We bring a consistent demonstration of the HgSe CQD doping decrease by a charge transfer to the POM. This method is highly promising for large tuning of carrier density in degenerately doped semiconductor nanoparticles.

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Section: Introductionmentioning

confidence: 99%

Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals

et al. 2018

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“…Among potential candidates, mercury chalcogenides (HgS 6,7 , HgSe [8][9][10] and HgTe 11 ) are the most mature materials, combining a tunable infrared absorption 12,13 with photoconductive 14 properties. In spite of huge progresses reported over the past decades 15 , which include the report of photovoltaic devices 16 , intraband transition based photodetector 1,17 , plasmonic devices 18,19 and multicolor devices 20,21 , no rational design of the material has been conducted.…”

Section: Introductionmentioning

confidence: 99%

Probing Charge Carrier Dynamics to Unveil the Role of Surface Ligands in HgTe Narrow Band Gap Nanocrystals

et al. 2017

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Abstract:Colloidal nanocrystals are an interesting platform for the design of low cost optoelectronic devices especially in the infrared range of wavelengths. Mercury chalcogenides have reached high maturity to address wavelengths above the telecom range (1.5 µm). However, no screening of the surface chemistry influence has been conducted yet. In this paper, we systematically probe the influence of a series of ligands: Cl -, SCN -, 1,2 ethanedithiol, 1,4 benzenedithiol, 1 octanethiol, 1 butanethiol, As 2 S 3 , S 2-on the photoconductive properties of HgTe nanocrystal thin films. A high bandwidth, large dynamic transient photocurrent setup is used to determine the photocarrier dynamics. Two regimes are clearly identified. At early stage (few ns) a fast decay of the photocurrent is resulting from recombination and trapping. Then transport enters in a multiple trapping regime where carriers present a continuously decreasing effective value of their mobility. The power law dependence of the conductance can be used to estimate the trap carrier density and determine the value of the Urbach energy (35 to 50 meV). We demonstrate that a proper choice of ligand is necessary for a trade-off between the material performance (µτ product) and the quality of the surface passivation (to keep a low Urbach energy).

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“…2(d). Parallel to this work, self-doped nanocrystals of HgS [28,29], HgSe [24,25,30] and HgTe [31,32] started to be synthesized. Their absorption spectrum typically presents two contributions: one at high energy (visible and near IR) attributed to interband transition and one in the mid infrared due to an intraband transition, see Fig.…”

Section: Narrow Band Gap Nanocrystalsmentioning

confidence: 96%

“…Doping is a critical aspect for obtaining an intraband absorption. HgS [28,29], HgSe [24,30,25] and HgTe [32] have been described as self-doped materials since no extrinsic impurities are introduced during the growth. However, the presence of free electrons requires some compensating charges to keep the material neutral.…”

Section: Intraband Transition In Nanocrystalsmentioning

confidence: 99%

Emergence of intraband transitions in colloidal nanocrystals [Invited]

Jagtap¹,

Livache²,

Martinez³

et al. 2018

Opt. Mater. Express

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The chemistry of nanocrystals enables the receipt of semiconductor nanoparticles with tunable optical properties. So far most scientific efforts have been focused on wide band gap materials to achieve a bright luminescence and a higher solar power conversion efficiency. Their properties in the infrared range of wavelengths are interesting as well. Two strategies can be used to achieve mid-infrared (mid-IR) transition, either interband transition in narrow band gap material or intraband transition in doped material. In this review, we discuss recent progress to achieve stable doped nanocrystals. We focus on mercury chalcogenide compounds since they are so far the only materials that combine mid-IR absorption with photoconductive properties in this range of energies. We discuss the origin of the doping and its tunability as well as how the doping impacts the optical, transport, and photodetection properties. Finally, we discuss Hg-free alternative materials, and present mid-IR transitions.

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High electron mobility of β-HgS colloidal quantum dots with doubly occupied quantum states

Abstract: Steady-state electron occupation of the lowest quantum state in the conduction band of a colloidal quantum dot gives rise to unique electrical properties. An electron mobility of 1.29 cm2 V−1 s−1 was measured in a mercury sulfide quantum dot FET.

Cited by 19 publications

References 21 publications

Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals

Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals

Probing Charge Carrier Dynamics to Unveil the Role of Surface Ligands in HgTe Narrow Band Gap Nanocrystals

Emergence of intraband transitions in colloidal nanocrystals [Invited]

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