Chaotic laser voltage: An electronic entropy source

Wishon, Michael J.; Li, Nianqiang; Choi, Daeyoung; Citrin, D. S.; Locquet, Alexandre

doi:10.1063/1.5025433

Cited by 9 publications

(2 citation statements)

References 36 publications

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“…Zero phonon line (ZPL) associated with the electron or hole capture process is expressed as the energy difference between the conduction band minimum E CBM and charge transition level E q 1 / q 2 for electron capture, or the energy difference between charge transition level E q 1 / q 2 and the valence band maximum E VBM for hole capture , ZPL capt . e = E CBM − E q 1 / q 2 ZPL capt . h = E q 1 / q 2 − E VBM in the case of complex defects, we calculated the binding energy defined as E b = normalΔ H f q 1 ( A ) + normalΔ H f q 2 ( B ) − normalΔ H f q 3 ( AB ) + prefix∑ j = 1 3 q j E F where Δ H f q 1 ( A ) is the formation energy of component A in charge state q 1 at Fermi level E F , Δ H f q 2 ( B ) is the formation energy of component B in charge state q 2 at Fermi level E F , Δ H f q 3 ( AB ) is the formation energy of complex AB in charge state q 3 at Fermi level E F . According to this definition, positive binding energy indicates a tendency toward cluster formation. , …”

Section: Methodsmentioning

confidence: 99%

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Atomistic Origins of Various Luminescent Centers and n-Type Conductivity in GaN: Exploring the Point Defects Induced by Cr, Mn, and O through an Ab Initio Thermodynamic Approach

Czelej,

Mansoor,

Sarsil

et al. 2024

Chem. Mater.

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GaN is a technologically indispensable material for various optoelectronic properties, mainly due to the dopantinduced or native atomic-scale point defects that can create single photon emitters, a range of luminescence bands, and n-or p-type conductivities. Among the various dopants, chromium and manganese-induced defects have been of particular interest over the past few years, because some of them contribute to our presentday light-emitting diode (LED) and spintronic technologies. However, the nature of such atomistic centers in Cr and Mndoped GaN is yet to be understood. A comprehensive defect thermodynamic analysis of Cr-and Mn-induced defects is essential for their engineering in GaN crystals because by mapping out the defect stabilities as a function of crystal growth parameters, we can maximize the concentration of the target point defects. We therefore investigate chromium and manganese-induced defects in GaN with ab initio methods using the highly accurate exchange− correlation hybrid functionals, and the phase transformations upon excess incorporation of these dopants using the CALPHAD method. We also investigate the impact of oxygen codoping that can be unintentionally incorporated during crystal growth. Our analysis sheds light on the atomistic cause of the unintentional n-type conductivity in GaN, being O N -related. In the case of Cr doping, the formation of Cr Ga defects is the most dominant, with an E +/0 charge transition at E VBM + 2.19 eV. Increasing nitrogen partial pressure tends to enhance the concentration of Cr Ga . However, in the case of doping with Mn, several different Mn-related centers can form depending on the growth conditions, with Mn Ga being the most dominant. Mn Ga possesses the E 2+/+ , E +/0 , and E 0/− charge transitions at 0.56, 1.04, and 2.10 eV above the VBM. The incorporation of oxygen tends to cause the formation of the Mn Ga −V Ga center, which explains a series of prior experimental observations in Mn-doped GaN. We provide a powerful tool for point defect engineering in wide band gap binary semiconductors that can be readily used to design optimal crystal growth protocols.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Atomistic Origins of Various Luminescent Centers and n-Type Conductivity in GaN: Exploring the Point Defects Induced by Cr, Mn, and O through an Ab Initio Thermodynamic Approach

Czelej,

Mansoor,

Sarsil

et al. 2024

Chem. Mater.

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Optical Centers in Cr-, Mn-, and O-Doped AlN and Their Thermodynamic Stability Designed by a Multiscale Computational Approach

Mansoor,

Sarsil,

Mansoor

et al. 2024

ACS Appl. Mater. Interfaces

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The optical centers in AlN can frequently exist in various charge states and can be accompanied by many coexisting defect species, creating a complex environment where mutual interactions are inevitable. Therefore, it is an immediate quest to design AlN crystal growth protocols that can target a specific optical center of interest and tune its concentration while preventing the formation of other unwanted point defects. Here, we provide a powerful workflow for point defect engineering in wide band gap, binary semiconductors that can be readily used to design optimal crystal growth protocols through combining CALPHAD-based phase analysis, and ab initio defect calculations. We investigate technologically relevant chromium-and manganeseinduced optical centers in AlN, followed by studying the impact of oxygen that can be unintentionally incorporated during crystal growth. We present the dominant defects in all three cases as a function of process parameters along with the optical signatures. In the case of both Cr and Mn doping, the Cr Al and Mn Al defects are most likely, and increasing nitrogen partial pressure tends to enhance their concentration. We show that it is possible to use nitrogen fugacity as a tool for tuning the intensity of optical signatures. We calculate the Cr Al charge transition levels with respect to the valence-band maximum at 2.60 eV (E +/− ), 3.83 eV (E 0/− ), and 5.41 eV (E −/2− ) and electron and hole capture transitions with luminescence bands centered at 2.82, 1.91, and 3.15 eV. Unlike the Cr doping, Mn aggregation is unlikely, and the Mn Al −V N is the most abundant defect after Mn Al under most synthesis conditions. Oxygen tends to form complexes with V Al , and O N −V Al is a prominent defect following O N , with near-UV emission bands at 3.17, 3.26, and 3.81 eV. Our results agree with the available experimental optical signatures of Cr-, Mn-, and O-related centers and provide pathways on how to tune the luminous intensity of these centers through changes in growth conditions.

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Random number generation from a quantum tunneling diode

Aungskunsiri

Amarit

Wongpanya

et al. 2021

Applied Physics Letters

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February, 2020Random number generation is important in many activities such as communication, encryption, science, gambling, finance, and decisionmaking. Quality of random numbers is critical in some applications, especially in cryptography, which require true randomness. In this work, we propose exploitation of a commercially-available quantum tunnelling diode as a source of true randomness. This off-the-shelf device is inexpensive and has a promising capability for future electronic integration at large-scale production.

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Chaotic laser voltage: An electronic entropy source

Cited by 9 publications

References 36 publications

Atomistic Origins of Various Luminescent Centers and n-Type Conductivity in GaN: Exploring the Point Defects Induced by Cr, Mn, and O through an Ab Initio Thermodynamic Approach

Atomistic Origins of Various Luminescent Centers and n-Type Conductivity in GaN: Exploring the Point Defects Induced by Cr, Mn, and O through an Ab Initio Thermodynamic Approach

Optical Centers in Cr-, Mn-, and O-Doped AlN and Their Thermodynamic Stability Designed by a Multiscale Computational Approach

Random number generation from a quantum tunneling diode

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