The Origin of Field-induced Electron Emission from N-doped CVD Diamond Characterized by Combined XPS/UPS/FES System
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1039-P15-11
The Origin of Field-induced Electron Emission from N-doped CVD Diamond Characterized by Combined XPS/UPS/FES System Hisato Yamaguchi1,2, Yuki Kudo1, Tomoaki Masuzawa1, Yoshifumi Shiraki1, Ichitaro Saito3, Masato Kudo4, Takatoshi Yamada5, Yuji Takakuwa6, and Ken Okano1,2 1 Department of Physics, International Christian University, 3-10-2 Osawa, Mitaka, Tokyo, 181-8585, Japan 2 School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1, Asahidai, Nomi, Ishikawa, 923-1292, Japan 3 Department of Engineering, University of Cambridge, 9, JJ Thomson Avenue, Cambridge, CB3 0FA, United Kingdom 4 JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo, 196-8558, Japan
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Diamond Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan 6 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan ABSTRACT The origin of field-emitted electrons for hydrogen-terminated natural IIb diamond was investigated as a reference to define the origin of field-emitted electrons from lightly nitrogen (N)-doped chemical vapor deposition (CVD) diamond. Using our combined X-ray photoelectron spectroscopy / ultraviolet photoelectron spectroscopy / field emission spectroscopy (XPS/UPS/FES) system, we determined the origin of field-emitted electrons for the natural diamond. The energy level of field-emitted electrons was at valence band maximum (VBM) and the origin of field-emitted electrons was independent of applied voltages. The results suggested the observed shift for FES peak of lightly N-doped CVD diamond is most likely due to the resistance of the diamond bulk. The FES Peak Energy Emission Current characteristics was best fitted to straight lines, and the resistance of the diamond was consistent with the resistance obtained from the slope. In addition, an attempt was made to define the origin of field-induced electron emission for heavily N-doped CVD diamond. The result suggested a possibility of conduction band minimum (CBM) as an origin of emitted electrons. INTRODUCTION There have been hundreds of studies on electron emission from diamond [1-7]. The discovery of negative electron affinity (NEA) [8] and the development of the chemical vapor
deposition (CVD) technique [9] accelerated research in the field. However, the emission mechanism has not been clarified, largely due to the difficulty in determining the origin of emitted electrons. The origin cannot directly be determined using conventional emission current - anode voltage (I-V) characteristics. Electron energy distribution is the method that directly provides the origin of emitted electrons. The origin can be defined simply by comparing the kinetic energy of emitted electrons and the electronic structure of the material [10-12]. Bandis et al. [10] clearly showed the advantage of using electron energy distribution for determination of the origin of field-emitted electrons. The result defined the or
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