Electron Emission Mechanism of Doped CVD Diamond Characterized Using Combined XPS/UPS/FES System
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0956-J11-06
Electron Emission Mechanism of Doped CVD Diamond Characterized Using Combined XPS/UPS/FES System Hisato Yamaguchi1, Ichitaro Saito2, Yuki Kudo3, Tomoaki Masuzawa3, Takatoshi Yamada4, Masato Kudo5, Yuji Takakuwa6, and Kem Okano1,3 1
School of Materials science, Japan Advanced Institute of Science and Technology, 1-1 Asashidai, Nomi, Ishikawa, 923-1292, Japan
2
Department of Engineering, University of Cambridge, 9, JJ Thompson Avenue, Cambridge, CB3 0FA, United Kingdom
3
Department of Physics, International Christian University, 3-10-2 Osawa, Mitaka, Tokyo, 181-8585, Japan
4
Diamond Research Center, AIST, 1-1-1 Umezono, Tsukuba, 305-8568, Japan
5
Technical Division 1, JEOL, 3-1-2 Musashino, Akishima, Tokyo, 196-8558, Japan
6
IMRAM, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
ABSTRACT Electric field of less than 5 V/µm is enough to extract electrons from diamond, whereas field of one to two orders of magnitude higher is needed to extract electrons from metal emitter tips. Despite such low-threshold field, the difficulty in clarification of electron emission mechanism is the factor preventing diamond from being used in a practical application. Quite a few numbers of possible mechanisms were proposed to better understand the origin and properties of the observed emission. Most of these mechanisms, however, were based on the conventional I-V (Emission current-Anode voltage) characteristics. Energy distribution of the field-emitted electrons is essential in direct clarification of the mechanism. In this study, combined XPS/UPS/FES system was used to characterize the electron emission mechanism of doped chemical vapor deposited (CVD) diamond. The results indicated successful observation of the origin of field-emitted electrons from doped CVD diamond comparison with natural diamond, used as a reference. INTRODUCTION Electric field of less than 5 V/µm is enough to extract electrons from diamond, whereas field of one to two orders of magnitude higher is needed to extract electrons from metal emitter tips. Diamond has various advantages as an electron emitter in addition to the low-threshold field, such as negative electron affinity (NEA), high thermal conductivity, high mechanical hardness, and high chemical stability. Despite advantages of the diamond as an electron emitter, however, the difficulty in clarification of electron emission mechanism is the
factor preventing diamond from being used in a practical application. Heavily nitrogen (N)-doped diamond, reported in 1996 by Okano et al. has gained much attention due to its extremely low threshold electric field, as low as 0.5V/µm [1]. Although quite a few numbers of possible mechanisms were proposed to better understand the origin and properties of the observed emission [2-4], most of these mechanisms were based on the conventional I-V (Emission current-Anode voltage) characteristics. Energy distribution of the field-emitted electrons is essential in direct clarification of the mechanism. It enables one to draw the energy band
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