Oscillatory regularity of charge carrier traps energy spectra in silicon organic polymer poly(di-n-hexylsilane)

Abstract

Charge carrier traps energy spectra have been investigated in silicon organic polymer poly(di-n-hexylsilane) by fractional thermally stimulated luminescence in the temperature range from 5 to 200 K. The energy spectrum of traps has been found to be discrete in nature, not the quasi-continuous, as it was considered earlier. It has been established that the traps energies form two characteristic series resulting from the vibrational quanta at 373 and 259 cm -1 , respectively. It is important that these vibrational quanta coincide with the frequencies of the totally symmetric vibrational modes of silicon chain which are active in Raman spectrum. The regularities mentioned are analyzed using the oscillatory traps model as the basis.

Interaction of Optical Vibrations With Charge Traps and the Thermoluminescence Spectra of Polymers

“…2), which was predicted by the model developed in [20]. The model suggested in [19] cannot explain the coincidence of the activation energy with the energy of vibrations. Therefore, we use the model suggested in [20], which explains this coincidence and predicts the appearance of the structure.…”

“…This makes it possible to increase the registration sensitivity by 2-3 orders of magnitude, as compared with that used for the detection of the integral TSL curves of other polymers. As a result, this allows one to get more than 85 heating fractions in the temperature range of 5-40 K. It was noted that the maximum number of fractions within the traditional methods [21,22] was not more than 20-30 fractions in the temperature range [18,19].…”

“…At the same time, the molecular vibrations manifest themselves in various optical properties of polymers: in absorption, luminescence, and Raman scattering. The connection between the activation energies of the traps of charge carriers and the energies of optical vibrations of the polymer backbone observed in the Raman spectra [16,17] has been recently obtained in [18,19], by using the TSL spectra of PDHS films. A model was proposed in [20] for the explanation of these results.…”

Fine structure of thermoluminescence assisted by molecular vibrations in disordered organic semiconductors

“…The authors of a number of papers [2,3] reported that molecular movements play a role in the carrier release from traps and that finds manifestation in the thermoluminescence. Unusual results were obtained in the works [4,5] devoted to the investigation of poly(di-n-hexylsilane) at low temperatures by the fractional TSL. The results showed the presence of pronounced discrete levels, though the spectrum of localized states in the polymer free from impurities or defects should be quasi-continuous.…”

“…Usually this process involves many vibrations and describes by the Arrhenius formula exp(−|E a |/κT), where T is the temperature, E a is the activation energy. The peculiarities observed in experiments [4,5] were explained in [8] under assumption of the existence of a process, in which a release of carrier from a trap may occur via the absorption by carrier of the separate quantum of molecular vibration with energy equal to the activation energy of the carrier. It explain the coincidence of the activation energy and the energy of the quantum of molecular vibrations obtained from Raman spectra.…”