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Title: Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators

Abstract

We report on a comparative study of transfer doping of hydrogenated single crystal diamond surface by insulators featured by high electron affinity, such as Nb{sub 2}O{sub 5}, WO{sub 3}, V{sub 2}O{sub 5}, and MoO{sub 3}. The low electron affinity Al{sub 2}O{sub 3} was also investigated for comparison. Hole transport properties were evaluated in the passivated hydrogenated diamond films by Hall effect measurements, and were compared to un-passivated diamond films (air-induced doping). A drastic improvement was observed in passivated samples in terms of conductivity, stability with time, and resistance to high temperatures. The efficiency of the investigated insulators, as electron accepting materials in hydrogenated diamond surface, is consistent with their electronic structure. These surface acceptor materials generate a higher hole sheet concentration, up to 6.5 × 10{sup 13} cm{sup −2}, and a lower sheet resistance, down to 2.6 kΩ/sq, in comparison to the atmosphere-induced values of about 1 × 10{sup 13} cm{sup −2} and 10 kΩ/sq, respectively. On the other hand, hole mobilities were reduced by using high electron affinity insulator dopants. Hole mobility as a function of hole concentration in a hydrogenated diamond layer was also investigated, showing a well-defined monotonically decreasing trend.

Authors:
; ;  [1]; ; ;  [2]
  1. Dip. di Ingegneria Industriale, Università di Roma “Tor Vergata,” Via del Politecnico 1, I-00133 Roma (Italy)
  2. Dip. di Ingegneria Elettronica, Università di Roma “Tor Vergata,” Via del Politecnico 1, I-00133 Roma (Italy)
Publication Date:
OSTI Identifier:
22597868
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 2; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AFFINITY; ALUMINIUM OXIDES; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; DIAMONDS; DOPED MATERIALS; ELECTRONIC STRUCTURE; ELECTRONS; HALL EFFECT; HOLE MOBILITY; HYDROGEN; HYDROGENATION; MOLYBDENUM OXIDES; MONOCRYSTALS; NIOBIUM OXIDES; SURFACES; TUNGSTATES; TUNGSTEN OXIDES; VANADATES; VANADIUM OXIDES

Citation Formats

Verona, C., Marinelli, Marco, Verona-Rinati, G., Ciccognani, W., Colangeli, S., and Limiti, E. Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators. United States: N. p., 2016. Web. doi:10.1063/1.4955469.
Verona, C., Marinelli, Marco, Verona-Rinati, G., Ciccognani, W., Colangeli, S., & Limiti, E. Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators. United States. doi:10.1063/1.4955469.
Verona, C., Marinelli, Marco, Verona-Rinati, G., Ciccognani, W., Colangeli, S., and Limiti, E. 2016. "Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators". United States. doi:10.1063/1.4955469.
@article{osti_22597868,
title = {Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators},
author = {Verona, C. and Marinelli, Marco and Verona-Rinati, G. and Ciccognani, W. and Colangeli, S. and Limiti, E.},
abstractNote = {We report on a comparative study of transfer doping of hydrogenated single crystal diamond surface by insulators featured by high electron affinity, such as Nb{sub 2}O{sub 5}, WO{sub 3}, V{sub 2}O{sub 5}, and MoO{sub 3}. The low electron affinity Al{sub 2}O{sub 3} was also investigated for comparison. Hole transport properties were evaluated in the passivated hydrogenated diamond films by Hall effect measurements, and were compared to un-passivated diamond films (air-induced doping). A drastic improvement was observed in passivated samples in terms of conductivity, stability with time, and resistance to high temperatures. The efficiency of the investigated insulators, as electron accepting materials in hydrogenated diamond surface, is consistent with their electronic structure. These surface acceptor materials generate a higher hole sheet concentration, up to 6.5 × 10{sup 13} cm{sup −2}, and a lower sheet resistance, down to 2.6 kΩ/sq, in comparison to the atmosphere-induced values of about 1 × 10{sup 13} cm{sup −2} and 10 kΩ/sq, respectively. On the other hand, hole mobilities were reduced by using high electron affinity insulator dopants. Hole mobility as a function of hole concentration in a hydrogenated diamond layer was also investigated, showing a well-defined monotonically decreasing trend.},
doi = {10.1063/1.4955469},
journal = {Journal of Applied Physics},
number = 2,
volume = 120,
place = {United States},
year = 2016,
month = 7
}
  • Although the two-dimensional hole gas (2DHG) of a hydrogen-terminated diamond surface provides a unique p-type conducting layer for high-performance transistors, the conductivity is highly sensitive to its environment. Therefore, the surface must be passivated to preserve the 2DHG, especially at high temperature. We passivated the surface at high temperature (450 °C) without the loss of C-H surface bonds by atomic layer deposition (ALD) and investigated the thermal reliability of the Al{sub 2}O{sub 3} film. As a result, C-H bonds were preserved, and the hole accumulation effect appeared after the Al{sub 2}O{sub 3} deposition by ALD with H{sub 2}O as an oxidant.more » The sheet resistivity and hole density were almost constant between room temperature and 500 °C by the passivation with thick Al{sub 2}O{sub 3} film thicker than 38 nm deposited by ALD at 450 °C. After the annealing at 550 °C in air The sheet resistivity and hole density were preserved. These results indicate the possibility of high-temperature application of the C-H surface diamond device in air. In the case of lower deposition temperatures, the sheet resistivity increased after air annealing, suggesting an insufficient protection capability of these films. Given the result of sheet resistivity after annealing, the increase in the sheet resistivity of these samples was not greatly significant. However, bubble like patterns were observed in the Al{sub 2}O{sub 3} films formed from 200 to 400 °C by air annealing at 550 °C for 1 h. On the other hand, the patterns were no longer observed at 450 °C deposition. Thus, this 450 °C deposition is the sole solution to enabling power device application, which requires high reliability at high temperatures.« less
  • The stability of C{sub 60} during collisions with a hydrogen-terminated diamond (111) surface was studied by using molecular dynamics simulations. At a collision energy of 150 eV only nonreactive collisions occur. At higher energies nonreactive scattering and two types of reactive collisions occur: (1) exchange of one or more atoms between the molecule and the surface; (2) chemisorption of the C{sub 60} molecule. No dissociation of the rebounding molecules was observed on the time scale of the simulations. However, the scattered molecules contain a large amount of internal energy, which suggests that dissociation may occur at longer times.
  • Atomic-force and Kelvin-probe microscopies were employed in ultrahigh vacuum to image the surface topography and contact potential of the hydrogen-terminated and unterminated surfaces of diamond. A variation of about 25 meV in the contact potential was measured on a length scale of 20 nm and ascribed to differently orientated surface domains resulting from hydrogen-plasma processing of the sample. Shifts in the work function arising from sample heating in vacuum and the adsorption of C{sub 60} were measured. The Fermi level was found to be 0.7 and 1.1 eV below the valence band maximum for C{sub 60} coverages of 1 andmore » 4 monolayer, respectively.« less