Search

This paper reports the relationship between the heat treatments of the CoFeB/MgO/CoFeB/Ta-based magnetic tunnel junction (MTJ) and the chemical bonding state using angle-resolved hard X-ray photoelectron spectroscopy. The redox reaction for B 1s during postannealing was verified for the MTJ without a capping layer by oxidizing the metallic B 1s in CoFeB and reducing the oxidized Fe 2p and Co 2p near the surface. For the MTJ with a capping layer, regardless of the heat treatments, MgO was found to be in a peroxidized state, and the diffusion of O 1s and B 1s exerted by the heat treatments is considered to be controlled by the degree of crystallization of MgO. The composition at the MgO/CoFeB interface changes on account of the heat treatments since the ratio of CoFeB and TaB at the bottom changes as a result of boron diffusion through the grain boundaries in MgO. By postannealing at 400 °C, the peak binding energy of Mg 1s at the surface was found to shift slightly to lower energy toward the stoichiometric MgO. However, the release of the excess oxygen in MgO is suppressed by the crystallization. Since the crystallization of MgO is enhanced by the in situ IR heating, the internal oxygen is more constrained in MgO. An improvement of the tunneling magnetoresistance deterioration observed with an ultrathin MgO is considered to be achieved under the peroxidized state controlled by the crystallinity of MgO. [ABSTRACT FROM AUTHOR]

Soft x-ray-excited angle-resolved photoemission results for nitride films formed using nitrogen–hydrogen radicals on Si(100), Si(111), and Si(110) are reported. The data were obtained using synchrotron radiation, which allowed the Si 2p, N 1s, and O 1s levels to be investigated with the same probing depth. The following main results were obtained: (1) the Si3N4 film is covered with one monolayer of Si–(OH)3N. Its areal density is 15% smaller on Si(111) than on Si(100) and Si (110), (2) the Si3N4/Si interfaces on all three surfaces are compositionally abrupt. This conclusion is based on the observation that no Si atoms bonded with three N atoms and one Si atom were detected, and (3) the observation that the number of Si–H bonds at the Si3N4/Si(110) interface is 38%–53% larger than those at the Si3N4/Si(100) and Si3N4/Si(111) interfaces indicates a dependence of the interface structure on the orientation of the substrate. [ABSTRACT FROM AUTHOR]

The chemical bonding states of boron (B) in shallow P+/N junctions on Si substrates were studied by soft x-ray photoelectron spectroscopy (SXPES). This study revealed three chemical bonding states of B embedded in bulk Si. The concentration profiles of B were successfully determined by combining SXPES with step-by-step etching of Si substrates. The concentration profiles of B thus determined were in good agreement with those determined by secondary ion mass spectroscopy. The concentration profiles of holes were also determined by combining Hall measurements with the step-by-step etching of Si substrates. The concentration profiles of B having the lowest binding energy were found to agree well with the concentration profiles of holes. Therefore, B with the lowest binding energy can be assigned as activated B and those having the middle and highest binding energies can be attributed to deactivated B having chemical bonding states different from that of activated B. [ABSTRACT FROM AUTHOR]

The soft x-ray-excited angle-resolved photoemission results for nitride films formed by using nitrogen-hydrogen radicals on Si(100), Si(111), and Si(110) are described. The abruptness of compositional transition at the [Si.sub.3][N.sub.4]/Si interface and the structure of silicon nitride films are clarified by using angle-resolved photoelectron spectroscopy.

The hard x-ray photoelectron spectroscopy (HX-PES) technique is employed for a complete analysis of the different subgap electronic states present in the amorphous oxide semiconductor, a-In-Ga-Zn-O. The various effects caused by thermal annealing on these subgap states of the system are also discussed.

A correction is offered for the article Erratum: "Angle-Resolved Phototelectron Study on the Structures of Silicon Nitride Films and Si3N4/Si Interfaces Formed Using Nitrogen-Hydrogen Radicals" in a previous issue.