Influence of molecular oxygen on h-BN/metal heterostructures

Переведенное название: Влияние молекулярного кислорода на h-BN-металл гетероструктуры.

Виктор Олегович Шевелев (автор и редактор), Кирилл Андреевич Бокай, Александр Вячеславович Федоров, Дмитрий Юрьевич Усачев

Результат исследований: Материалы конференцийтезисы

Выдержка

Two-dimensional (2D) materials remain in the focus of intensive research directed towards their applications in future spintronics. It was shown theoretically that in order to inject highly spinpolarized current from ferromagnetic metal into graphene implementation of an insulating tunnel
barrier is needed [1]. Nowadays, the most promising insulating layer for this purpose is an ultrathin hexagonal boron nitride (h-BN).
To date, the most notable heterostructure where the tunnel spin injection into graphene was directly demonstrated is based on the h-BN/Co interface [2]. Production of such heterostructures involves transfer of CVD-grown graphene on top of h-BN/Co system. During this process and further using the system inevitably gets in contact with molecular oxygen, so it is important to know how O2 molecules affect the h-BN/Co interface. Currently, interaction of molecular oxygen with h-BN/Co system remains completely unexplored.
Thus, in this work we demonstrate a comprehensive study of molecular oxygen reaction with hBN on Co and Au surfaces, which possess different chemical activity and interaction with h-BN. For this purpose, two samples of h-BN were synthesized on Co(0001) substrate. Afterwards, Au intercalation was carried out under one of them. Both samples were annealed in oxygen atmosphere at temperature of 300C; after each stage of annealing XPS and NEXAFS spectra were measured. Data analysis shows that h-BN reacts with oxygen on both surfaces, but in different ways. Comparison of experimental data with DFT calculations allows us to propose following mechanism of h-BN oxidation on cobalt. Oxygen molecules penetrate between h-BN and Co, where they dissociate and active O atoms are further incorporated into h-BN lattice with substitution of N atoms.
In the case of h-BN/Au oxidation occurs much more slowly. Presence of Au monolayer under h-BN leads to significant decreasing of oxygen dissociation rate that results in low reactivity. Prolonged annealing leads to etching of h-BN. NEXAFS map at the edge of Co absorption shows forming of islands of cobalt oxide on the whole area in the field of view. We suppose that different mechanism of h-BN oxidation takes place; O atoms do not substitute N atoms inside h-BN lattice. We believe that in the case of h-BN/Au reaction proceeds mainly along the borders of h-BN layer. We suppose that at the areas of surface, where h-BN was etched, Au atoms form clusters and open the path to Co
surface for oxygen.
This work was supported by Saint Petersburg State University Grant 11.65.42.2018 and RFBR Grant No. 17-02-00427 А.

[1] A. Fert et. al., Conditions for efficient spin injection from a ferromagnetic metal into a
semiconductor, Phys. Rev. B, 2001, 64, 184420.
[2] M. V. Kamalakar et. al., Inversion of Spin Signal and Spin Filtering in Ferromagnet|Hexagonal
Boron Nitride-Graphene van der Waals Heterostructures, Scientific Reports, 2016, 6, 1
Язык оригиналаанглийский
Страницы54
Число страниц2
СостояниеОпубликовано - 2018

Отпечаток

boron nitrides
oxygen
metals
graphene
atoms
oxidation
tunnels
substitutes
annealing
cobalt oxides
borders
intercalation

Цитировать

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title = "Influence of molecular oxygen on h-BN/metal heterostructures",
abstract = "Two-dimensional (2D) materials remain in the focus of intensive research directed towards their applications in future spintronics. It was shown theoretically that in order to inject highly spinpolarized current from ferromagnetic metal into graphene implementation of an insulating tunnel barrier is needed [1]. Nowadays, the most promising insulating layer for this purpose is an ultrathin hexagonal boron nitride (h-BN).To date, the most notable heterostructure where the tunnel spin injection into graphene was directly demonstrated is based on the h-BN/Co interface [2]. Production of such heterostructures involves transfer of CVD-grown graphene on top of h-BN/Co system. During this process and further using the system inevitably gets in contact with molecular oxygen, so it is important to know how O2 molecules affect the h-BN/Co interface. Currently, interaction of molecular oxygen with h-BN/Co system remains completely unexplored.Thus, in this work we demonstrate a comprehensive study of molecular oxygen reaction with hBN on Co and Au surfaces, which possess different chemical activity and interaction with h-BN. For this purpose, two samples of h-BN were synthesized on Co(0001) substrate. Afterwards, Au intercalation was carried out under one of them. Both samples were annealed in oxygen atmosphere at temperature of 300C; after each stage of annealing XPS and NEXAFS spectra were measured. Data analysis shows that h-BN reacts with oxygen on both surfaces, but in different ways. Comparison of experimental data with DFT calculations allows us to propose following mechanism of h-BN oxidation on cobalt. Oxygen molecules penetrate between h-BN and Co, where they dissociate and active O atoms are further incorporated into h-BN lattice with substitution of N atoms.In the case of h-BN/Au oxidation occurs much more slowly. Presence of Au monolayer under hBN leads to significant decreasing of oxygen dissociation rate that results in low reactivity. Prolonged annealing leads to etching of h-BN. NEXAFS map at the edge of Co absorption shows forming of islands of cobalt oxide on the whole area in the field of view. We suppose that different mechanism of h-BN oxidation takes place; O atoms do not substitute N atoms inside h-BN lattice. We believe that in the case of h-BN/Au reaction proceeds mainly along the borders of h-BN layer. We suppose that at the areas of surface, where h-BN was etched, Au atoms form clusters and open the path to Cosurface for oxygen.This work was supported by Saint Petersburg State University Grant 11.65.42.2018 and RFBR Grant No. 17-02-00427 А.",
author = "Шевелев, {Виктор Олегович} and Бокай, {Кирилл Андреевич} and Федоров, {Александр Вячеславович} and Усачев, {Дмитрий Юрьевич}",
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Influence of molecular oxygen on h-BN/metal heterostructures. / Шевелев, Виктор Олегович (автор и редактор); Бокай, Кирилл Андреевич; Федоров, Александр Вячеславович; Усачев, Дмитрий Юрьевич.

2018. 54.

Результат исследований: Материалы конференцийтезисы

TY - CONF

T1 - Influence of molecular oxygen on h-BN/metal heterostructures

AU - Бокай, Кирилл Андреевич

AU - Федоров, Александр Вячеславович

AU - Усачев, Дмитрий Юрьевич

A2 - Шевелев, Виктор Олегович

PY - 2018

Y1 - 2018

N2 - Two-dimensional (2D) materials remain in the focus of intensive research directed towards their applications in future spintronics. It was shown theoretically that in order to inject highly spinpolarized current from ferromagnetic metal into graphene implementation of an insulating tunnel barrier is needed [1]. Nowadays, the most promising insulating layer for this purpose is an ultrathin hexagonal boron nitride (h-BN).To date, the most notable heterostructure where the tunnel spin injection into graphene was directly demonstrated is based on the h-BN/Co interface [2]. Production of such heterostructures involves transfer of CVD-grown graphene on top of h-BN/Co system. During this process and further using the system inevitably gets in contact with molecular oxygen, so it is important to know how O2 molecules affect the h-BN/Co interface. Currently, interaction of molecular oxygen with h-BN/Co system remains completely unexplored.Thus, in this work we demonstrate a comprehensive study of molecular oxygen reaction with hBN on Co and Au surfaces, which possess different chemical activity and interaction with h-BN. For this purpose, two samples of h-BN were synthesized on Co(0001) substrate. Afterwards, Au intercalation was carried out under one of them. Both samples were annealed in oxygen atmosphere at temperature of 300C; after each stage of annealing XPS and NEXAFS spectra were measured. Data analysis shows that h-BN reacts with oxygen on both surfaces, but in different ways. Comparison of experimental data with DFT calculations allows us to propose following mechanism of h-BN oxidation on cobalt. Oxygen molecules penetrate between h-BN and Co, where they dissociate and active O atoms are further incorporated into h-BN lattice with substitution of N atoms.In the case of h-BN/Au oxidation occurs much more slowly. Presence of Au monolayer under hBN leads to significant decreasing of oxygen dissociation rate that results in low reactivity. Prolonged annealing leads to etching of h-BN. NEXAFS map at the edge of Co absorption shows forming of islands of cobalt oxide on the whole area in the field of view. We suppose that different mechanism of h-BN oxidation takes place; O atoms do not substitute N atoms inside h-BN lattice. We believe that in the case of h-BN/Au reaction proceeds mainly along the borders of h-BN layer. We suppose that at the areas of surface, where h-BN was etched, Au atoms form clusters and open the path to Cosurface for oxygen.This work was supported by Saint Petersburg State University Grant 11.65.42.2018 and RFBR Grant No. 17-02-00427 А.

AB - Two-dimensional (2D) materials remain in the focus of intensive research directed towards their applications in future spintronics. It was shown theoretically that in order to inject highly spinpolarized current from ferromagnetic metal into graphene implementation of an insulating tunnel barrier is needed [1]. Nowadays, the most promising insulating layer for this purpose is an ultrathin hexagonal boron nitride (h-BN).To date, the most notable heterostructure where the tunnel spin injection into graphene was directly demonstrated is based on the h-BN/Co interface [2]. Production of such heterostructures involves transfer of CVD-grown graphene on top of h-BN/Co system. During this process and further using the system inevitably gets in contact with molecular oxygen, so it is important to know how O2 molecules affect the h-BN/Co interface. Currently, interaction of molecular oxygen with h-BN/Co system remains completely unexplored.Thus, in this work we demonstrate a comprehensive study of molecular oxygen reaction with hBN on Co and Au surfaces, which possess different chemical activity and interaction with h-BN. For this purpose, two samples of h-BN were synthesized on Co(0001) substrate. Afterwards, Au intercalation was carried out under one of them. Both samples were annealed in oxygen atmosphere at temperature of 300C; after each stage of annealing XPS and NEXAFS spectra were measured. Data analysis shows that h-BN reacts with oxygen on both surfaces, but in different ways. Comparison of experimental data with DFT calculations allows us to propose following mechanism of h-BN oxidation on cobalt. Oxygen molecules penetrate between h-BN and Co, where they dissociate and active O atoms are further incorporated into h-BN lattice with substitution of N atoms.In the case of h-BN/Au oxidation occurs much more slowly. Presence of Au monolayer under hBN leads to significant decreasing of oxygen dissociation rate that results in low reactivity. Prolonged annealing leads to etching of h-BN. NEXAFS map at the edge of Co absorption shows forming of islands of cobalt oxide on the whole area in the field of view. We suppose that different mechanism of h-BN oxidation takes place; O atoms do not substitute N atoms inside h-BN lattice. We believe that in the case of h-BN/Au reaction proceeds mainly along the borders of h-BN layer. We suppose that at the areas of surface, where h-BN was etched, Au atoms form clusters and open the path to Cosurface for oxygen.This work was supported by Saint Petersburg State University Grant 11.65.42.2018 and RFBR Grant No. 17-02-00427 А.

M3 - Abstract

SP - 54

ER -