Iridium is a promising substrate for self-limiting growth of graphene. However, single-crystalline graphene can only be fabricated over 1120 K. The weak interaction between graphene and Ir makes it challenging to grow...Iridium is a promising substrate for self-limiting growth of graphene. However, single-crystalline graphene can only be fabricated over 1120 K. The weak interaction between graphene and Ir makes it challenging to grow graphene with a single orientation at a relatively low temperature. Here, we report the growth of large-scale, single-crystalline graphene on Ir(111) substrate at a temperature as low as 800 K using an oxygen-etching assisted epitaxial growth method. We firstly grow polycrystalline graphene on Ir. The subsequent exposure of oxygen leads to etching of the misaligned domains.Additional growth cycle, in which the leftover aligned domain serves as a nucleation center, results in a large-scale and single-crystalline graphene layer on Ir(111). Low-energy electron diffraction, scanning tunneling microscopy, and Raman spectroscopy experiments confirm the successful growth of large-scale and single-crystalline graphene. In addition, the fabricated single-crystalline graphene is transferred onto a SiO_2/Si substrate. Transport measurements on the transferred graphene show a carrier mobility of about 3300 cm^2·V^(-1)·s^(-1). This work provides a way for the synthesis of large-scale,high-quality graphene on weak-coupled metal substrates.展开更多
n-Si（111） surface tailed -C2H5, -C2H4COOH, -C2H2COOH were prepared by the reactions among Si-H to ethyl-Grignard, methyl acrylate and ethyl propionate, and the carboxyls were formed under the existence of trifluoroa...n-Si（111） surface tailed -C2H5, -C2H4COOH, -C2H2COOH were prepared by the reactions among Si-H to ethyl-Grignard, methyl acrylate and ethyl propionate, and the carboxyls were formed under the existence of trifluoroacetic acid. The composite n-Si（111） electrodes were obtained by depositing Pt nanodots and the photovoltaic characteristics for these electrodes were studied in I^-/I3^- redox electrolyte. The j-U （photo current density-potential） behaviors of photo-voltage and photocurrent densities to the electrodes under solar illumination varied regularly with groups of -C2H2COOH〉-C2H4COOH〉-H〉-C2H5. The photo-voltage and photocurrent density of the electrode tailed -C2 H2COOH were -0.641 V and 5.25 mA/cm^2, respectively, more negative than those of the non-conjugated modification.展开更多
The magneto-transport properties of （111）-oriented single-crystal thin films of SnTe were investigated. SnTe （111） thin films were epitaxially grown on a BaF2 substrate by molecular beam epitaxy. By optimizing the...The magneto-transport properties of （111）-oriented single-crystal thin films of SnTe were investigated. SnTe （111） thin films were epitaxially grown on a BaF2 substrate by molecular beam epitaxy. By optimizing the growth conditions and the thickness of the films, the bulk carrier density could be reduced, making it possible to detect the surface transport. Magneto-conductance （MC） measurements show a cusp-like feature around zero magnetic field, which is attributed to the weak-antilocalization effect of the transport in the topological surface state. Detailed analysis of this negative MC reveals a reduced number of transport channels contributing to the surface transport, suggesting strong coupling between Dirac valleys on the SnTe （111） surface, as a characteristic feature of the transport in the multivalley structure of topological crystalline insulators.展开更多
Using the effect of the temperature on the capacitance–voltage（C–V）and conductance–voltage（G/ω–V）characteristics of PtSi/n-Si（111）Schottky diodes the profile of apparent doping concentrationthe potential di...Using the effect of the temperature on the capacitance–voltage（C–V）and conductance–voltage（G/ω–V）characteristics of PtSi/n-Si（111）Schottky diodes the profile of apparent doping concentrationthe potential difference between the Fermi energy level and the bottom of the conduction bandapparent barrier heightseries resistanceand the interface state density Nss have been investigated.From the temperature dependence of（C–V）it was found that these parameters are non-uniformly changed with increasing temperature in a wide temperature range of 79–360 K.The voltage and temperature dependences of apparent carrier distribution we attributed to the existence of self-assembled patches similar the quantum wells,which formed due to the process of Pt Si formation on semiconductor and the presence of hexagonal voids of Si（111）.展开更多
基金Project supported by the National Key Research&Development Program of China(Grant Nos.2016YFA0202300 and 2018YFA0305800)the National Natural Science Foundation of China(Grant Nos.61888102 and 51872284)+2 种基金the Chinese Academy of Sciences(CAS)Pioneer Hundred Talents Program,the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB30000000 and XDB28000000)Beijing Nova Program,China(Grant No.Z181100006218023)the University of Chinese Academy of Sciences
文摘Iridium is a promising substrate for self-limiting growth of graphene. However, single-crystalline graphene can only be fabricated over 1120 K. The weak interaction between graphene and Ir makes it challenging to grow graphene with a single orientation at a relatively low temperature. Here, we report the growth of large-scale, single-crystalline graphene on Ir(111) substrate at a temperature as low as 800 K using an oxygen-etching assisted epitaxial growth method. We firstly grow polycrystalline graphene on Ir. The subsequent exposure of oxygen leads to etching of the misaligned domains.Additional growth cycle, in which the leftover aligned domain serves as a nucleation center, results in a large-scale and single-crystalline graphene layer on Ir(111). Low-energy electron diffraction, scanning tunneling microscopy, and Raman spectroscopy experiments confirm the successful growth of large-scale and single-crystalline graphene. In addition, the fabricated single-crystalline graphene is transferred onto a SiO_2/Si substrate. Transport measurements on the transferred graphene show a carrier mobility of about 3300 cm^2·V^(-1)·s^(-1). This work provides a way for the synthesis of large-scale,high-quality graphene on weak-coupled metal substrates.
基金We are grateful to the Project of the National Natural Science Foundation of China(Grant No.50602004)the support from Chinese Education for Back Student Abroad and the fund for Young Teacher of BUCT(Project No.QN0512)for financial support.
文摘n-Si（111） surface tailed -C2H5, -C2H4COOH, -C2H2COOH were prepared by the reactions among Si-H to ethyl-Grignard, methyl acrylate and ethyl propionate, and the carboxyls were formed under the existence of trifluoroacetic acid. The composite n-Si（111） electrodes were obtained by depositing Pt nanodots and the photovoltaic characteristics for these electrodes were studied in I^-/I3^- redox electrolyte. The j-U （photo current density-potential） behaviors of photo-voltage and photocurrent densities to the electrodes under solar illumination varied regularly with groups of -C2H2COOH〉-C2H4COOH〉-H〉-C2H5. The photo-voltage and photocurrent density of the electrode tailed -C2 H2COOH were -0.641 V and 5.25 mA/cm^2, respectively, more negative than those of the non-conjugated modification.
文摘The magneto-transport properties of （111）-oriented single-crystal thin films of SnTe were investigated. SnTe （111） thin films were epitaxially grown on a BaF2 substrate by molecular beam epitaxy. By optimizing the growth conditions and the thickness of the films, the bulk carrier density could be reduced, making it possible to detect the surface transport. Magneto-conductance （MC） measurements show a cusp-like feature around zero magnetic field, which is attributed to the weak-antilocalization effect of the transport in the topological surface state. Detailed analysis of this negative MC reveals a reduced number of transport channels contributing to the surface transport, suggesting strong coupling between Dirac valleys on the SnTe （111） surface, as a characteristic feature of the transport in the multivalley structure of topological crystalline insulators.
文摘Using the effect of the temperature on the capacitance–voltage（C–V）and conductance–voltage（G/ω–V）characteristics of PtSi/n-Si（111）Schottky diodes the profile of apparent doping concentrationthe potential difference between the Fermi energy level and the bottom of the conduction bandapparent barrier heightseries resistanceand the interface state density Nss have been investigated.From the temperature dependence of（C–V）it was found that these parameters are non-uniformly changed with increasing temperature in a wide temperature range of 79–360 K.The voltage and temperature dependences of apparent carrier distribution we attributed to the existence of self-assembled patches similar the quantum wells,which formed due to the process of Pt Si formation on semiconductor and the presence of hexagonal voids of Si（111）.
