Two-dimensional alloy of immiscible metals: Single and binary monolayer films of Pb and Sn on Rh(111)

The single and binary metal films of Pb and Sn on Rh(111) have been studied at room temperature by scanning tunneling microscopy (STM), low-energy electron diffraction, and Auger electron spectroscopy. Both Pb and Sn are mobile at low coverage and form commensurate overlayers of (4*4)-Pb and c(2*4)-Sn, respectively. From atomically resolved STM images, the atomic arrangements of (4*4)-Pb and c(2*4)-Sn have been identified to be hexagonal and rectangular structures, respectively. With increasing coverage, both commensurate phases change into incommensurate phases followed by island formation (Stranski-Krastanov growth). This shows that Rh(111) is static and inert enough to support two-dimensional (2D) phases of Pb and/or Sn without alloying at room temperature. The Pb-Sn bimetallic film on Rh(111) forms an ordered 2D alloy of PbSn_3 with an incommensurate structure close to (√7*√7), contrary to the immiscibility of Pb and Sn in the bulk. From atomically resolved STM images, the atomic arrangement of this (√7*√7)-(Pb,Sn) structure has been determined.journal articl

第08号

一般雑誌記事 / Articlearticl

Improved measurement of CP-violation parameters sin⁡2ϕ1 and |λ|, B meson lifetimes, and B0-B̅0 mixing parameter Δmd

journal articl

Optical Evaluation of Miniband Formation in InGaAs/GaAsP Quantum Well Solar Cells

To investigate the effect of the miniband formation on the optical properties, we adopted three non-destructive methods of piezoelectric photothermal (PPT), photoluminescence (PL), and photoreflectance (PR) spectroscopies for strain-balanced InGaAs/GaAsP superlattice structure inserted GaAs p-i-n solar cells. From PR measurements, a critical energy corresponding to the subband transition of e1-hh1 was estimated for thick barrier samples, whereas two critical energies corresponding to the mini-Brillouin-zone center (Γ) and edge (Π) were obtained for 2.0-nm thin barrier sample. The PPT and PL spectra of 2.0-nm thin barrier sample also showed the different behaviors than thick barrier samples. The peak positions were located at lower photon energy side because of lowering the transition energy between Γ of e1 miniband and hh1. It was confirmed that the miniband formation causes the redshifts of the optical absorption (PPT) and radiative recombination (PL) processes.departmental bulletin pape

身分登記簿廃止にみるわが国の戸籍法事情 ―近代法形成期の経験―

application/pdf田中利幸教授退職記念号departmental bulletin pape

Non-Radiative Carrier Recombination and Carrier Transport Properties in the Multiple Quantum Well Solar Cell

To investigate the carrier generation, thermal escape, and recombination processes in the strain-balanced InGaAs/GaAsP multiple quantum well (MQW) structure into GaAs p-i-n solar cell, the frequency-dependent piezoelectric photothermal (PPT) method was adopted. Since the thermal diffusion length of the signal source decreases with increasing the chopping frequency, we investigated the depth profile of non-radiative recombination carrier loss. Two distinctive peaks were observed in the lower photon energy region below the bandgap of GaAs (Eg, 1.42 eV at RT) for the MQW structure inserted sample. They were caused by the excitonic absorption associated with the inter-subband transitions within the MQWs. Although PPT signal intensity at above the bandgap of GaAs decreased with increasing the chopping frequency, the signal intensity at MQW remained even at high frequency. These features are explainable in terms that photoexcited carriers thermally escape from MQW and diffuse to the GaAs substrate. Diffused carriers then recombine at GaAs substrate non-radiatively.departmental bulletin pape