Barrier Height Difference Induced by Surface Terminations for Field Emission from P-doped Diamond
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1039-P15-12
Barrier Height Difference Induced by Surface Terminations for Field Emission from Pdoped Diamond Yuki Kudo1, Takatoshi Yamada2, Hisato Yamaguchi1, Tomoaki Masuzawa1, Ichitaro Saito1, Shin-ichi Shikata2, Christoph E. Nebel2, and Ken Okano1 1 Department of Physics, International Christian University (ICU), 3-10-2 Osawa, Mitaka, Tokyo, 185-8585, Japan 2 Diamond Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan ABSTRACT In this paper, we measured the field emission properties of reconstructed P-doped diamond under various anode-diamond distances and compared with the oxidized surface. Voltage drops in the vacuum was estimated to be 4.95 and 26.6 V/µm for the reconstructed and the oxidized, respectively. Moreover, we calculated the barrier height ratio between each surface. Our data indicates the changes in electron affinity strongly affect on the field emission properties. INTRODUCTION Cold cathodes are important components of vacuum nano-electronic devices and field emission displays [1]. For practical products, cold cathode having both low vacuum operation and low driven voltages are required. Diamond could be one of the best candidates that satisfy both these requirements at the same time, because of a negative or small positive electron affinity of diamond surface and high chemical and physical stabilities. There are large numbers of reports on field emission from chemical vapor deposited diamonds. However, it was difficult to utilise negative electron affinity of H-terminated diamond surface. Majority of reports were related to field emitted electrons originating from valence band maximum [2-3] because boron-doped p-type semiconducting or intrinsic diamonds were used. The energy barrier heights for field emission are effectively high due to limited number of electrons in conduction band. In 1997, deposition of n-type diamond was achieved by doping phosphorus (P) [4-5]. Moreover, negative electron affinity on a n-type diamond terminated with hydrogen was reported [6]. These suggested that P-doped diamond allow us to utilise electrons in conduction band for field emission. In fact, field emission properties of P-doped diamond were characterized and low threshold voltage from P-doped diamond surface was reported compared to the B-doped diamond [7-9]. Furthermore, we recently reported that carbon reconstructed heavily P-doped diamond with small positive electron affinity shows a low threshold voltage and a stable field emission current among various surface termination on heavily P-doped diamonds [9-11]. It is suggested that the P-doped diamond can reduce an applied voltage dramatically by simple process of annealing the surface in a vacuum. However, emission mechanism from these surfaces has not been clarified. In this paper, we measured the field emission properties of reconstructed P-doped diamond under various anode-diamond distances [3,12] and compared the results to the oxidized surfaces. Using field emission pro
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