The influence of the space charge on The Ohm's law conservation in CVD diamond layers

In present work we report the investigation of charge transport mechanism in thin diamonds layer grown by hot filament chemical vapor deposition (HF CVD) method. The measurements were performed in both, wide temperature and bias voltage ranges as well. In the disordered matter the variable range hop...

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Bibliographic Details
Published in:Carbon (New York) 2019-03, Vol.143, p.413-418
Main Authors: Łoś, Szymon, Paprocki, Kazimierz, Fabisiak, Kazimierz, Szybowicz, Mirosław
Format: Article
Language:English
Subjects:
Carbon
Charge transport
Chemical vapor deposition
Conductivity
Crystal defects
Depletion
Diamond films
Diamonds
Electrons
Helium atoms
Impedance spectroscopy
Ohm's Law
Organic chemistry
Point defects
Raman
Semiconductors
Space charge
Surface resistivity
Temperature dependence
Thin films
Wide bandgap semiconductors
XRD
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Summary:In present work we report the investigation of charge transport mechanism in thin diamonds layer grown by hot filament chemical vapor deposition (HF CVD) method. The measurements were performed in both, wide temperature and bias voltage ranges as well. In the disordered matter the variable range hopping mechanism can play a crucial role. The obtained results reveal that simultaneously holes and electrons are involved in current flow. They can be easily distinguished by their different dynamics detected by impedance spectroscopy. The diamond crystal is considered as a wide bandgap semiconductor. Hole states originated as point defects inside of the bandgap behave like usual charges in semiconductor and they obey the Ohm's law. However, the CVD diamond polycrystalline films always contains some amount of sp2 hybridized amorphous carbon phase. This form of carbon can donate electrons to the system. Electrons gathered as space charge on diamond edges create a depletion layer with unlike properties. The Ohm's law is broken for such type of charges and their activation energy are temperature dependent. At temperature of 21 K a sudden change of surface resistivity is observed, when helium atoms are being adsorbed on slowly moving holes. [Display omitted]
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2018.11.043