High-Throughput Study of Compositions and Optical Properties in Heavily Co-Doped Silicon Nanoparticles

Somogyi, B; Derian, René; Štich, Ivan; Gali, Ádám

doi:10.1021/acs.jpcc.7b09501

Cited by 14 publications

(15 citation statements)

References 72 publications

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“…With their surface chemistry modifications and optimal carrier multiplication features they might tackle both of these problems at the same time. In parallel to these co-doped structures, singly doped (n- or p-type) Si NCs have shown their value for the optoelectronic industry as well and could be employed as, for example, fluorescent markers for biosensing purposes , or even photodetectors …”

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confidence: 99%

Critical Size for Carrier Delocalization in Doped Silicon Nanocrystals: A Study by Ultrafast Spectroscopy

et al. 2018

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We present a comprehensive ultrafast spectroscopy-based study on the delocalization of doping-induced carriers in Si nanocrystals (NCs). To this end we prepare thin films of differently sized doped Si NCs and vary the doping configurations from singly P and B doping to simultaneously P and B co-doping. We show that the NC size orchestrates the level of delocalization of the doping-induced carriers. This can be understood in light of (1) the quantum confinement effect and (2) unscreened Coulomb interactions by moving further into the nanoscale. Both contributions affect the activation energy (ΔE) that is required to create free majority carriers. By varying the NC size in combination with the doping configuration we tune ΔE and control the delocalization of the doping-induced carriers. Most importantly, we show that there is a critical NC diameter of D critical ≈ 6 nm that describes the transition from a localized to a free carrier regime. In particular, our results show that optical bandgaps of ∼0.95 eV (optimal for carrier multiplication-facilitated solar cell power conversion) can be achieved in P−B co-doped Si NCs with D NC < D critical . These results indicate that the practical photovoltaic feasibility of co-doped Si NCs is not limited by the presence of some remaining free carriers in uncompensated NCs.

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confidence: 99%

Critical Size for Carrier Delocalization in Doped Silicon Nanocrystals: A Study by Ultrafast Spectroscopy

et al. 2018

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“…The previous studies either dealt with very small fragments , or modeled the QD structure by crystalline models . Because the QDs are amorphous, at least in their outer shells, such approximations severely limit the accuracy of the models.…”

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confidence: 99%

“…18 Somogyi et al performed a DFT study on a system containing a larger number of B and P (e.g., 5 B and 5 P atoms) by the timedependent density functional theory. 24,25 They studied the correlation between the configurations of dopants and the optical band gaps of codoped Si QDs for hundreds of QDs and identified the most stable dopant configurations. They also studied how the photoluminescence, infrared absorption, and Raman scattering spectra are modified by codoping.…”

Section: ■ Introductionmentioning

confidence: 99%

“…26 The previous studies either dealt with very small fragments 23,27 or modeled the QD structure by crystalline models. 25 Because the QDs are amorphous, at least in their outer shells, such approximations severely limit the accuracy of the models. We quenched the QD structures from the melt using DFT-based molecular dynamics methods, which naturally take into account the presence of disorder, the directional bonds in silicon, the complex multicenter bonding in boron, 28 and the three-component nature of our QDs that requires one to correctly describe bonding between six different atom pairs.…”

Section: ■ Introductionmentioning

confidence: 99%

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Structure and Properties of Heavily B and P Codoped Amorphous Silicon Quantum Dots

et al. 2021

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Colloidal silicon quantum dots feature a number of outstanding properties, such as size and termination controlled band gap and photoluminescence, which, in combination with nontoxicity, make them suitable for biomedical applications. Because of the presence of structural disorder and experimental limitations, the atomic structure, especially of the small sub 2.5 nm dots, is not well known. We have developed computational techniques that allow us to model the atomic structures of the small dots and have applied them to heavily B and P codoped Si quantum dots and studied their structural, electronic, and vibrational properties. The study confirms that the structures of the smallest dots are fully amorphous with the onset of formation of a quasi-crystalline core in the larger ones. The models give insights into the dopant distribution in the dot. We find that the core morphology depends strongly on the chemical composition of the dot. Study of the electronic and vibrational properties gives insights into their localization properties and allows validation of the generated models by comparison with experiments. The degree of agreement of the properties of our simulated dots with those from experiments suggests that the fine details in preparation protocols may not critically affect their structure and properties.

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“…[1][2][3][4][5]7,8 In particular, doped silicon quantum dots have shown promise in photovoltaic and photonic applications due to their size tunability and processability. 6,9,10 A key dopant property is its activation energy, which often behaves differently in the nanoscale. For example, when P-(phosphorus) and B-(boron) dopants are introduced to bulk Si, they create shallow impurity states that can act as donors/acceptors of charge carriers.…”

Section: Introductionmentioning

confidence: 99%

Dopant levels in large nanocrystals using stochastic optimally tuned range-separated hybrid density functional theory

Lee,

Chen,

et al. 2020

Preprint

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We apply a stochastic version of an optimally tuned range-separated hybrid (OT-RSH) functional to provide insight on the electronic properties of P-and B-doped Si nanocrystals of experimentally relevant sizes. We show that we can use the range-separation parameter for undoped systems to calculate accurate results for dopant activation energies. We apply this strategy for tuning functionals to study doped nanocrystals up to 2.5 nm in diameter at the hybrid functional level. In this confinement regime, the P-and B-dopants have large activation energies and have strongly localized states that lie deep within the energy gaps. Structural relaxation plays a greater role for B-substituted dopants and contributes to the increase in activation energy when the B dopant is near the nanocrystal surface.

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High-Throughput Study of Compositions and Optical Properties in Heavily Co-Doped Silicon Nanoparticles

Cited by 14 publications

References 72 publications

Critical Size for Carrier Delocalization in Doped Silicon Nanocrystals: A Study by Ultrafast Spectroscopy

Critical Size for Carrier Delocalization in Doped Silicon Nanocrystals: A Study by Ultrafast Spectroscopy

Structure and Properties of Heavily B and P Codoped Amorphous Silicon Quantum Dots

Dopant levels in large nanocrystals using stochastic optimally tuned range-separated hybrid density functional theory

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