Enhanced Secondary Electron Emission in Nanoscale Thin Metal Containing MgO Film: Laser Irradiation on Creation of F Centers

Abstract

A number of oxygen vacancies were found in the MgO film when a nanoscale-metal embedded MgO film (MgO/nanoscale metal film/MgO) was exposed to a pulsed KrF excimer laser. This was due to the interfacial reaction between embedding nanoscale metal and MgO film. In a case of Nb embedding metal, the Nb 2 O 5 crystallites were evidenced to proceed the reaction at the MgO/Nb interface; 5MgO + 2Nb f Nb 2 O 5 + 5Mg + 5V O 3 3 . The oxygen vacancies formed the F centers in the MgO bandgap, resulting in high cathodoluminescence intensity at the 431 and 526 nm region, corresponding to F + and F centers. The F centers in MgO played a role in increasing secondary electron emission coefficient (γ). As several kinds of nanoscale metals for creating F centers (Cr, Ti, V, In, Ta, and Nb) were embedded into MgO film, the γ values were found to be inversely linear with the ΔG f for the formation of metal oxides. The Nb embedded MgO film showed the highest γ value of ∼0.232 compared with normal MgO film (0.034).

Compositional and Geometrical Effects of Bimetallic Cu–Sn Catalysts on Selective Electrochemical CO2 Reduction to CO

“…To clearly identify the distribution of Sn NPs, Fourier filtering was performed by masking SnO(200) (Figure 2b2) and SnO 2 (220) patterns (Figure 2b3). 36 The Fourier-filtered images and electron diffraction pattern (Figure 2b4) confirmed that SnO and SnO 2 NPs were coated on the Cu surface and had a size of 2 to 6 nm. After t c = 60 s, the TEM image (Figure 2c1) showed d spacings of 0.335, 0.264, 0.212, 0.247, and 0.181 nm, which correspond to the SnO 2 (110), SnO 2 (101), SnO 2 (210), Cu 2 O(111), and Cu(200) planes, respectively.…”

“…After coating Sn NPs on the 3D-h Cu catalyst at coating time ( t c ) = 10 s, the TEM image and electron diffraction pattern showed d spacings of 0.190, 0.168, and 0.142 nm, which correspond to the SnO(200), SnO 2 (220), and CuO(022) planes, respectively (Figure b1). To clearly identify the distribution of Sn NPs, Fourier filtering was performed by masking SnO(200) (Figure b2) and SnO 2 (220) patterns (Figure b3) . The Fourier-filtered images and electron diffraction pattern (Figure b4) confirmed that SnO and SnO 2 NPs were coated on the Cu surface and had a size of 2 to 6 nm.…”

Mixed Films Based on MgO for Secondary Electron Emission Application: General Trends and MOCVD Prospects

“…The other nanoscale metals as Cr, Ti, V, In, and Ta were also able to create Fs centers increasing SEEC of composite although to a lesser degree [26]. The strategy of preparing a Zn-doped MgO layer on the surface of MgO/Au composite resulted in the higher SEEC that was kept constant all the time under continuous electron bombardment of 200 eV, and this improvement was the most effective due to electrical conductivity induced by Zn doping [23].…”

“…So, composites such as MgO/Au and Au/MgO modified by Zn and Al, showed high SEE, but despite modifying MgO, the films remained to be unstable during functioning [17][18][19][20][21][22][23][24]. The ALD fabrication of the Al 2 O 3 /MgO and MgO/Nb/MgO laminated composites with encapsulated MgO and nanoscale Nb layers was of interest for coating due to enhancement of SEEC [25,26]. This effect was explained via an occurrence of highly dispersed, conducting impurity Al particles distributed between the matrix grains [25] and via inducing the Fs center by embedded Nb metal in MgO during laser annealing [26].…”

Graphene growth controlled by the position and number of layers (n = 0, 1, and more than 2) using Ni and MgO patterned ultra-flat Cu foil

“…18,19 The MgO surface, which has a strong tendency to chemically bond with water molecules present in the ambient conditions by forming Mg(OH) 2 , has a low catalytic activity with carbo-hydroxyl molecules as well as low carbon solubility. 20 As a result, the MgO patterned area on Cu can be expected to have no layers of graphene. In addition, in order to obtain a at and high quality n-layer graphene surface, we have used extremely at hetero-catalytic (Ni patterned Cu foil) metal foils using the peel-off techniques based on our previous key ideas as shown in Fig.…”