Complex Dielectric Characteristics, ac-Conductivity, and Impedance Spectroscopy of B-Doped nc-SiO_X:H Thin Films

Abstract

Temperature-dependent ac conductivity, impedance spectroscopy, and complex dielectric properties have been investigated on boron-doped silicon oxide (SiO X :H) films grown by radio frequency plasma-enhanced chemical vapor deposition at low temperature (∼250 °C). The two-phase characteristics, e.g., silicon nanocrystals (Si-ncs) embedded in amorphous oxide (a-SiO X :H) tissues, have been evaluated initially by structural studies and subsequently via impedance spectroscopy. Impedance spectroscopy also facilitates identifying the contribution of each individual phase (nanocrystalline and amorphous) on the electronic properties of the materials. The dependence of relaxation time on temperature obeys Arrhenius behavior and also confirms a non-Debye type response under the varying electric field. The negative temperature coefficient of resistance behavior reveals the semiconducting nature of the materials. A designed equivalent circuit model using parallel R∥CPE shows comprehensive correlation among structural, microstructural, and charge carrier characteristics. Frequency-dependent conductivity follows Jonscher’s power law non-linear fitting and reveals a less than unity magnitude of its exponent “n”. The temperature dependence of ac conductance identifies a non-overlapping small polaron tunneling mechanism prevailing in the B-doped SiO X :H network. The tunneling distance is higher in B-doped nc-SiO X :H, and it reduces faster at higher frequency in the B-doped a-SiO X :H matrix. The charge carrier density of states, N(E F), is higher in nc-SiO X :H; however, the lower N(E F) of B-doped a-SiO X :H enhances faster at elevated frequency. The frequency-dependent electrical transport in the B-doped nanocrystalline/amorphous heterostructured SiO X :H network has never been explored before.

Negative Capacitance and Intrinsic Ferroelectric Behavior in α-MoO3 Culminating as a Robust Piezoelectric Energy Harvester

“…The electrical characteristics of MO were examined using the complex impedance [ Z ( f ) = Z ′( f ) – jZ ″( f )] spectroscopy technique, where Z ′ and Z ″ are the real and imaginary parts of Z , respectively. This method is most effective for identifying a material’s electrical characteristics, such as resistivity, carrier mobility, and carrier relaxation attributes . The experiment involved varying the frequency from 100 Hz to 50 MHz while maintaining the electric potential at V rms = 1 V. Figure a shows the real ( Z ′) and imaginary ( Z ″) parts of the complex impedance function Z (Ω).…”

Studies on the Impedance Characteristics, Dielectric Relaxation, and ac Conductivity in Silicon Oxycarbide (SiOxCy:H) Films at the Amorphous-to-Nanocrystalline Transition Zone

“…Information on the charge carrier lifetime in a material can be extracted from such a plot. The average lifetime, that is, the average time span for the excited conduction band electrons to recombine with a hole, has been computed using the equation τ e = 1/(2π f m ), in which f m is the Bode plot’s mid-frequency peak. , There are two different peaks in the spectra for films made at T S = 170 and 180 °C. The presence of nc-Si in the conduction process is linked to the appearance of a high-frequency peak, and the a-SiO x C y :H component contributes to the low-frequency peak.…”

“…The depressed nature of the semicircular arc identifies the presence of a nonideal capacitor-like element in the material. Accordingly, in the place of a capacitor, a constant phase element (CPE) is considered, which has the flexibility to switch from the ideal capacitor performance. , The first circuit involves a resistor R nc and, in parallel, a constant phase element CPE nc , both connected to the nc-Si component. The second circuit similarly connects a resistor R a and a parallel constant phase element CPE a related to the a-SiO x C y :H component.…”

“…Many frameworks can be intended to link the ac conduction mechanism with the s ( T ) behavior in finding the most likely conduction mechanism for the sample’s ac conductivity. The following theoretical frameworks are most relevant according to the existing literature: , The nonoverlapping small polaron tunneling (NSPT) model, wherein the frequency exponent ( s ) grows as temperature increases. The correlated barrier hopping model, wherein s declines as temperature increases. The overlapping large polaron tunneling model, wherein s is temperature- and frequency-dependent. On increasing the temperature, it reduces to a lower limit before growing as the temperature increases further. The quantum mechanical tunneling model, wherein s is ∼0.8 and it grows marginally with temperature or remains temperature-independent. …”

“…The dc electrical characteristics of these two-phase materials have been investigated in several studies. − However, ac electrical transport, impedance spectroscopy, and dielectric properties are studied only in a few studies, including two of the studies reported from our laboratory on B-doped nanocrystalline silicon oxide and P-doped silicon oxide thin films. − Impedance spectroscopy, dielectric property, and ac electrical transport study can explain various structural evolutions, defect state distribution, band tail defect dynamics, and many more. , Moreover, the ac electrical transport on nc-SiO x C y thin films is not available in the literature, to the best of our knowledge.…”