Sub-band gap photo-enhanced secondary electron emission from high-purity single-crystal chemical-vapor-deposited diamond

被引:3
作者
Yater, J. E. [1 ]
Shaw, J. L. [1 ]
Pate, B. B. [1 ]
Feygelson, T. I. [1 ]
机构
[1] Naval Res Lab, 4555 Overlook Ave SW, Washington, DC 20375 USA
关键词
CVD DIAMOND; FIELD-EMISSION; AFFINITY; FILMS; SPECTROSCOPY; ENERGIES; SURFACES; FEATURES; BANDGAP;
D O I
10.1063/1.4941020
中图分类号
O59 [应用物理学];
学科分类号
摘要
Secondary-electron-emission (SEE) current measured from high-purity, single-crystal (100) chemical-vapor-deposited diamond is found to increase when sub-band gap (3.06 eV) photons are incident on the hydrogenated surface. Although the light does not produce photoemission directly, the SEE current increases by more than a factor of 2 before saturating with increasing laser power. In energy distribution curves (EDCs), the emission peak shows a corresponding increase in intensity with increasing laser power. However, the emission-onset energy in the EDCs remains constant, indicating that the bands are pinned at the surface. On the other hand, changes are observed on the high-energy side of the distribution as the laser power increases, with a well-defined shoulder becoming more pronounced. From an analysis of this feature in the EDCs, it is deduced that upward band bending is present in the near-surface region during the SEE measurements and this band bending suppresses the SEE yield. However, sub-band gap photon illumination reduces the band bending and thereby increases the SEE current. Because the bands are pinned at the surface, we conclude that the changes in the band levels occur below the surface in the electron transport region. Sample heating produces similar effects as observed with sub-band gap photon illumination, namely, an increase in SEE current and a reduction in band bending. However, the upward band bending is not fully removed by either increasing laser power or temperature, and a minimum band bending of similar to 0.8 eV is established in both cases. The sub-band gap photo-excitation mechanism is under further investigation, although it appears likely at present that defect or gap states play a role in the photo-enhanced SEE process. In the meantime, the study demonstrates the ability of visible light to modify the electronic properties of diamond and enhance the emission capabilities, which may have potential impact for diamond-based vacuum electron sources, particle detectors, and other electronic devices.
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页数:9
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共 31 条
[1]   Simultaneous field emission and photoemission from diamond [J].
Bandis, C ;
Pate, BB .
APPLIED PHYSICS LETTERS, 1996, 69 (03) :366-368
[2]   ELECTRON-EMISSION DUE TO EXCITON BREAKUP FROM NEGATIVE ELECTRON-AFFINITY DIAMOND [J].
BANDIS, C ;
PATE, BB .
PHYSICAL REVIEW LETTERS, 1995, 74 (05) :777-780
[3]   Field emission and band bending considerations from high-quality NEA diamond [J].
Bandis, C ;
Pate, BB ;
Phillips, W ;
Plano, MA ;
Moyer, MD ;
Moreno, MA .
III-NITRIDE, SIC AND DIAMOND MATERIALS FOR ELECTRONIC DEVICES, 1996, 423 :771-776
[4]   Electron affinity of the bare and hydrogen covered single crystal diamond (111) surface [J].
Cui, JB ;
Ristein, J ;
Ley, L .
PHYSICAL REVIEW LETTERS, 1998, 81 (02) :429-432
[5]   NEA peak of the differently terminated and oriented diamond surfaces [J].
Diederich, L ;
Aebi, P ;
Küttel, OM ;
Schlapbach, L .
SURFACE SCIENCE, 1999, 424 (2-3) :L314-L320
[6]   TRAPPING LEVELS IN PULSE-COUNTING SYNTHETIC DIAMOND DETECTORS [J].
FALLON, PJ ;
NAM, TL ;
KEDDY, RJ .
DIAMOND AND RELATED MATERIALS, 1992, 1 (12) :1185-1189
[7]   QUANTUM PHOTOYIELD OF DIAMOND(111) - STABLE NEGATIVE-AFFINITY EMITTER [J].
HIMPSEL, FJ ;
KNAPP, JA ;
VANVECHTEN, JA ;
EASTMAN, DE .
PHYSICAL REVIEW B, 1979, 20 (02) :624-627
[8]   Sub-bandgap photoenhancement of electron emission and discharging of hydrogenated and hydrogen-free diamond surfaces [J].
Hoffman, A ;
Lafosse, A ;
Azria, R .
PHYSICAL REVIEW B, 2006, 73 (08)
[9]   Decay of secondary electron emission and charging of hydrogenated and hydrogen-free diamond film surfaces induced by low energy electrons [J].
Hoffman, A ;
Laikhtman, A ;
Ustaze, S ;
Hamou, MH ;
Hedhili, MN ;
Guillotin, JP ;
Le Coat, Y ;
Azria, R .
JOURNAL OF APPLIED PHYSICS, 2002, 91 (07) :4726-4732
[10]   Electron stimulated desorption from oxygenated and hydrogenated synthetic diamond films [J].
Hopman, HJ ;
Verhoeven, J ;
Bachmann, PK .
DIAMOND AND RELATED MATERIALS, 2000, 9 (3-6) :1238-1244