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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/17138

Title: Contactless Photoconductance Study on Undoped and Doped Nanocrystalline Diamond Films
Authors: Seshan, Venkatesh
Murthy, Dharmapura H. K.
Castellanos-Gomez, Andres
Sachdeva, Sumit
Ahmad, Hakeem A.
van der Zant, Herre S. J.
Sudholter, Ernst J. R.
Savenije, Tom J.
de Smet, Louis C. P. M.
Issue Date: 2014
Citation: ACS APPLIED MATERIALS & INTERFACES, 6 (14), p. 11368-11375
Abstract: Hydrogen and oxygen surface-terminated nanocrystalline diamond (NCD) films are studied by the contactless time-resolved microwave conductivity (TRMC) technique and X-ray photoelectron spectroscopy (XPS). The optoelectronic properties of undoped NCD films are strongly affected by the type of surface termination. Upon changing the surface termination from oxygen to hydrogen, the TRMC signal rises dramatically. For an estimated quantum yield of 1 for sub-bandgap optical excitation the hole mobility of the hydrogen-terminated undoped NCD was found to be similar to 0.27 cm(2)/(V s) with a lifetime exceeding 1 mu s. Assuming a similar mobility for the oxygen-terminated undoped NCD a lifetime of similar to 100 ps was derived. Analysis of the valence band spectra obtained by XPS suggests that upon oxidation of undoped NCD the surface Fermi level shifts (toward an increased work function). This shift originates from the size and direction of the electronic dipole moment of the surface atoms, and leads to different types of band bending at the diamond/air interface in the presence of a water film. In the case of boron-doped NCD no shift of the work function is observed, which can be rationalized by pinning of the Fermi level. This is confirmed by TRMC results of boron-doped NCD, which show no dependency on the surface termination. We suggest that photoexcited electrons in boron-doped NCD occupy nonionized boron dopants, leaving relatively long-lived mobile holes in the valence band.
Notes: [Seshan, Venkatesh; Murthy, Dharmapura H. K.; Sachdeva, Sumit; Ahmad, Hakeem A.; Sudholter, Ernst J. R.; Savenije, Tom J.; de Smet, Louis C. P. M.] Delft Univ Technol, Dept Chem Engn, NL-2628 BL Delft, Netherlands. [Seshan, Venkatesh; Castellanos-Gomez, Andres; van der Zant, Herre S. J.] Delft Univ Technol, Kavli Inst Nanosci, NL-2628 CJ Delft, Netherlands. [Murthy, Dharmapura H. K.] Dutch Polymer Inst, NL-5600 AX Eindhoven, Netherlands. [Janssens, Stoffel D.; Janssen, Wiebke; Haenen, Ken] Hasselt Univ, Inst Mat Res IMO, BE-3590 Diepenbeek, Belgium. [Janssens, Stoffel D.; Janssen, Wiebke; Haenen, Ken] IMEC Vzw, IMOMEC, BE-3590 Diepenbeek, Belgium. t.j.savenije@tudelft.nl; l.c.p.m.desmet@tudelft.nl
URI: http://hdl.handle.net/1942/17138
DOI: 10.1021/am501907q
ISI #: 000339472100070
ISSN: 1944-8244
Category: A1
Type: Journal Contribution
Validation: ecoom, 2015
Appears in Collections: Research publications

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