Electron affinity of cubic boron nitride terminated with vanadium oxide

Abstract

Submitted for the 4CF15 Meeting of The American Physical SocietyElectron affinity of cubic boron nitride terminated with vanadium-oxide YU YANG, TIANYIN SUN, JOSEPH SHAMMAS, MAN-PUNEET KAUR, MEI HAO, ROBERT NEMANICH, Arizona State University -H-terminated cubic boron nitride (c-BN) has been shown to exhibit a negative electron affinity (NEA) surface, which may enable applications in thermionic and photon-enhanced energy conversion devices. The ability to withstand high temperature operation is an important factor in the thermionic emission applications. Theoretical and experimental studies have indicated that transition metal oxides can significantly influence the electronic properties of diamond. In this study, a thermally stable NEA for a c-BN surface with vanadium-oxide-termination is achieved, and its electronic structure was analyzed with in-situ photoelectron spectroscopy. Thin vanadium layers of˜0.1 and 0.5 nm were deposited on the c-BN surface in an electron beam deposition system. Oxidation of the metal layer was achieved by an oxygen plasma treatment. After 650 o C thermal annealing, the vanadium oxide on the c-BN surface was determined to be VO 2 , and the surfaces were found to be thermally stable, exhibiting an NEA. In comparison, the oxygen-terminated c-BN surface, where B 2 O 3 was detected, showed a positive electron affinity (PEA) of˜1.2 eV. The B 2 O 3 evidently acts as a negatively charged layer introducing a surface dipole directed into the c-BN. Through the interaction of VO 2 with the B 2 O 3 layer, a B-O-V layer structure would contribute a dipole between the O and V layers with the positive side facing vacuum. The lower enthalpy of formation for B 2 O 3 is favorable for the formation of the B-O-V layer structure, which provides a thermally stable surface dipole and a NEA surface.

Structural and electronic properties of pristine and hydrogen-terminated c-BN(100) surfaces

“…This is supported by the experimental results of the H-terminated c-BN with negative electron affinity. 13,14,40…”

Heteroepitaxial growth of single-domain cubic boron nitride films by ion-beam-assisted MBE

“…Therefore, the c-BN films in previous reports are nonoriented polycrystalline. [10][11][12][13][14][15][16][17][18][19][20] We recently achieved the heteroepitaxial growth of phasepure c-BN(001) and (111) films on diamond (001) and (111) substrates by the ion-beam-assisted molecular beam epitaxy (MBE) method. 21) Furthermore, we revealed that a V=III ratio higher than 1 and a growth temperature (T g ) above 750 °C are necessary for the epitaxial growth of c-BN films on diamond substrates.…”

Tribological behavior of the low‐concentration boric acid and ZDDP lubricating oil mixtures

“…The peaks of O1s at binding energies of 530.1, 531.5, and 533.2 ± 1 eV were assigned to FeOSi, FeBO, and BOC bonds, respectively . Furthermore, the peak of O1s at 532.9 eV for substrates tested with 3 and 5% boric acid‐base oil corresponded to B 2 O 3 in 3.54 and 3.12% atomic quantity, respectively . The Fe2p3 peak presents iron oxides on the wear scar surface of the substrates tested with boric acid+base oil .…”

“…41,42 Furthermore, the peak of O1s at 532.9 eV for substrates tested with 3 and 5% boric acid-base oil corresponded to B 2 O 3 in 3.54 and 3.12% atomic quantity, respectively. 43,44 The Fe2p3 peak presents iron oxides on the wear scar surface of the substrates tested with boric acid+base oil. 45,46 Fe, S, P, Zn, and O elements were detected in the XPS analyses of wear scar surfaces of the substrates, which were lubricated by 1, 3, and 5% ZDDP+base oil due to the decomposition of ZDDP under heat and load (see Table 4 and Figure 11).…”