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Profiling of Current Transients in Capacitor Type Diamond Sensors.

Gaubas E, Ceponis T, Meskauskaite D, Kazuchits N - Sensors (Basel) (2015)

Bottom Line: The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed.The parameters of drift mobility of the electrons μ(e) = 4000 cm2/Vs and holes μ(h) = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents.The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Research, Vilnius University, Sauletekio av. 9-III, LT-10222 Vilnius, Lithuania. eugenijus.gaubas@ff.vu.lt.

ABSTRACT
The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo's theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μ(e) = 4000 cm2/Vs and holes μ(h) = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion D(a) = 97 cm2/s and the carrier recombination lifetime τ(R,CVD) ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond.

No MeSH data available.


Sketches of evolution of the light injected charges (large circles) under switched-on external voltage of rather small value and of the dynamic polarization through accumulation of the space charge under a set of light pulses (1st—a, 2nd—b, and N-th—c) those inject bulk density of excess carrier pairs (hollow and solid large circles). The dynamic depletion widths are denoted by Xe0 and Xh0. The diagrams of the capacitor charging currents (vertical lines) after each N-th light pulse are there shown on the right.
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sensors-15-13424-f004: Sketches of evolution of the light injected charges (large circles) under switched-on external voltage of rather small value and of the dynamic polarization through accumulation of the space charge under a set of light pulses (1st—a, 2nd—b, and N-th—c) those inject bulk density of excess carrier pairs (hollow and solid large circles). The dynamic depletion widths are denoted by Xe0 and Xh0. The diagrams of the capacitor charging currents (vertical lines) after each N-th light pulse are there shown on the right.

Mentions: Simplified sketches of the processes and the formation regimes for current pulses are illustrated in Figure 3, Figure 4, Figure 5 and Figure 6. In Figure 3, the energy and charge distributions are sketched for sensor biasing (a), for the phase of monopolar drift of the injected excess carriers (b), and for the polarization charge formation (c), under both the excess carrier trapping to deep centres (quasi-stationary polarization) and formation of the depletion (from one type of excess carriers) region at electrodes (dynamic polarization) after drifting excess carriers arrive to electrodes. Sketches of the evolution of the light injected bulk charge distribution and of the dynamic polarization through accumulation of the space charge under a set of light pulses those inject bulk density of excess carrier pairs are illustrated in Figure 4. In Figure 5, a sketch of separation and drift of the locally injected charges (of rather small amount) under switched-on external voltage of value capable to separate excess carrier pairs is presented. In Figure 6, sketches of the diffusion current formation under large amount of the light injected carrier pairs in the bulk of material within inter-electrode gap are illustrated, when a partial or complete screening of the external field by injected carriers appears.


Profiling of Current Transients in Capacitor Type Diamond Sensors.

Gaubas E, Ceponis T, Meskauskaite D, Kazuchits N - Sensors (Basel) (2015)

Sketches of evolution of the light injected charges (large circles) under switched-on external voltage of rather small value and of the dynamic polarization through accumulation of the space charge under a set of light pulses (1st—a, 2nd—b, and N-th—c) those inject bulk density of excess carrier pairs (hollow and solid large circles). The dynamic depletion widths are denoted by Xe0 and Xh0. The diagrams of the capacitor charging currents (vertical lines) after each N-th light pulse are there shown on the right.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507641&req=5

sensors-15-13424-f004: Sketches of evolution of the light injected charges (large circles) under switched-on external voltage of rather small value and of the dynamic polarization through accumulation of the space charge under a set of light pulses (1st—a, 2nd—b, and N-th—c) those inject bulk density of excess carrier pairs (hollow and solid large circles). The dynamic depletion widths are denoted by Xe0 and Xh0. The diagrams of the capacitor charging currents (vertical lines) after each N-th light pulse are there shown on the right.
Mentions: Simplified sketches of the processes and the formation regimes for current pulses are illustrated in Figure 3, Figure 4, Figure 5 and Figure 6. In Figure 3, the energy and charge distributions are sketched for sensor biasing (a), for the phase of monopolar drift of the injected excess carriers (b), and for the polarization charge formation (c), under both the excess carrier trapping to deep centres (quasi-stationary polarization) and formation of the depletion (from one type of excess carriers) region at electrodes (dynamic polarization) after drifting excess carriers arrive to electrodes. Sketches of the evolution of the light injected bulk charge distribution and of the dynamic polarization through accumulation of the space charge under a set of light pulses those inject bulk density of excess carrier pairs are illustrated in Figure 4. In Figure 5, a sketch of separation and drift of the locally injected charges (of rather small amount) under switched-on external voltage of value capable to separate excess carrier pairs is presented. In Figure 6, sketches of the diffusion current formation under large amount of the light injected carrier pairs in the bulk of material within inter-electrode gap are illustrated, when a partial or complete screening of the external field by injected carriers appears.

Bottom Line: The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed.The parameters of drift mobility of the electrons μ(e) = 4000 cm2/Vs and holes μ(h) = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents.The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Research, Vilnius University, Sauletekio av. 9-III, LT-10222 Vilnius, Lithuania. eugenijus.gaubas@ff.vu.lt.

ABSTRACT
The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo's theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μ(e) = 4000 cm2/Vs and holes μ(h) = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion D(a) = 97 cm2/s and the carrier recombination lifetime τ(R,CVD) ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond.

No MeSH data available.