E.O. Popov

Development of on-line emission parameters processing research technique of polymer-MWCNT emitters

The technique of record and in situ processing of data about evolution of multiwall carbon nanotubes polymer (MWCNT-polymer) field emitters was developed. It includes multichannel data acquisition system of current, voltage, vacuum level and temperature and computer on-line processing of these data by program which was written on LabView. We gained time dependence of field enhancement factor, height and number of emission sites, slope-interception diagram and voltage-current characteristics derivative.

Extracting formal emission area by on-line processing of current-voltage data, using FN-type equations for the Schottky-Nordheim barrier

We have implemented experimental methods for determining emission area parameters by using online processing of current-voltage characteristics (IVC). We calculated the formal emission area for each experimental IVC: for a single tungsten emitter and for several multi-tip emitters based on CNT and graphene. Voltage dependence in emission area is observed.

Emission structure stability investigation in alternating and reverse polarity electrical fields

Structure stability of a multiwall carbon nanotube - polystyrene nanocomposite was investigated in two operational modes. Statistical analysis of the emission parameters of the whiskers formed on the anode surface during field emission was carried out. The histograms of the statistical distribution of effective heights at different current levels were plotted. Mass-spectrometry data in alternating electrical fields show the presence of C2H2, H2 and CO in spectra.

Field emission and gases desorbtion of MWCNT emitters

The experimental results of polymeric nanocomposite emission characteristic dynamics and vacuum level deviation interrelation are presented. It is shown that there are distinctive values of the emission current defining further course of emission. The nanocomposite emission dynamic behavior is explained by the contribution of thermal emission and influence of adsorption-desorption processes.

Research of the polymer-MWCNT emitters in AC power supply

AC high voltage power supply impacts the emission stability of carbon polymeric nanocomposite. It is shown that threshold values of an electric field in the bipolar mode, related to the material transfer beginning from one electrode to another, are determined by the polymeric compound used in the nanocomposite emitter.

Current-voltage characteristic hysteresis dependence on power supply regime for large area field emitters

We investigated the hysteresis phenomenon in current-voltage characteristics of multipoint emitters based on nanocomposites with carbon nanotubes and graphene. The conditions under which the change in shape of the hysteresis from “direct” to “reverse” or vice versa occurs were found. Mass-spectrometer data allowed to associate hysteresis with adsorbed particles a source of which is the anode.

The technique of online analysis of the current-voltage characteristics of nanocomposite field emitters using the SK-charts

In the presented work, a new method of online processing of emission data is reported that allows us to estimate work function and geometrical parameters of the field nanostructures. The method is based on analysis of the Seppen-Katamuki chart for the current-voltage characteristics, which allows the construction of a calibration grid. Using this method, field emission characteristics of nanocomposites, with CNT and graphene as filler, were analyzed in various operating conditions.

Comparison of the data about thin IVC structure of multi-tip field emitters using a high voltage scanning method in different power supply mode and the data of the mass spectrometer analysis

We received and compared the current-voltage characteristics (IVC) of the multi-tip field nanocomposite emitters in the slow and the fast high voltage scanning modes. We found two types of hysteresis on the emission characteristics plots in the same field experiment. The study of IVC form depending on the duration and amplitude of the scanning voltage was carried out.

Further investigation of statistical parameters of nanocomposite multi-tip emitters

The advanced technique of current-voltage characteristic (IVC) on-line processing and recording was developed. It allows to observe and evaluate statistical dependences of the emission centers for nanostructured field emitters. Statistics and IVCs of the samples with different nanotubes length and radius were compared. The emitter based on carbon films modified by high-voltage vacuum discharge was also studied. Influence of the vacuum level in the interelectrode gap on the distribution of the emission centers was considered.

Real-time verification of current-voltage characteristics conformity to the classical field emission theory by ‘orthodoxy’ test

An experimental apparatus and a LabView-based software suite for real-time research on field emission were developed. The current-voltage characteristics of field emitters based on carbon nanotube/polymer nanocomposite were observed and analyzed using a simple quantitative test for lack of conformity with classical field emission theory.