Charge transport mechanisms and memory effects in amorphous TaN x thin films

Abstract

Amorphous semiconducting materials have unique electrical properties that may be beneficial in nanoelectronics, such as low leakage current, charge memory effects, and hysteresis functionality. However, electrical characteristics between different or neighboring regions in the same amorphous nanostructure may differ greatly. In this work, the bulk and surface local charge carrier transport properties of a-TaNx amorphous thin films deposited in two different substrates are investigated by conductive atomic force microscopy. The nitride films are grown either on Au (100) or Si [100] substrates by pulsed laser deposition at 157 nm in nitrogen environment. For the a-TaNx films deposited on Au, it is found that they display a negligible leakage current until a high bias voltage is reached. On the contrary, a much lower threshold voltage for the leakage current and a lower total resistance is observed for the a-TaNx film deposited on the Si substrate. Furthermore, I-V characteristics of the a-TaNx film deposited on Au show significant hysteresis effects for both polarities of bias voltage, while for the film deposited on Si hysteresis, effects appear only for positive bias voltage, suggesting that with the usage of the appropriate substrate, the a-TaNx nanodomains may have potential use as charge memory devices.

Synthesis of Amorphous InSb Nanowires and a Study of the Effects of Laser Radiation and Thermal Annealing on Nanowire Crystallinity

“…For the as-grown NW device, m = 3.2, while for NW that was annealed for 4 hrs the value of m decreases to 2 and for the NW that was annealed for 18 hours, m decreases further to 1.6. The high values of m are consistent with the space-charge-limited current (SCLC) conduction model [ 20 , 41 ]. A possible explanation for different transport mechanisms in the low and high bias regimes and for the changing m is the existence of a high density of defects at the metal-semiconductor interface.…”

“…Because of the disorder in a - , the band edges lose their sharpness and there exists a large density of localized states that tails into the energy band gap [ 18 , 19 ]. The localized electronic states causes carrier scattering, resulting in low carrier mobility, and also induces charge trapping [ 19 , 20 ]. Despite the fact that amorphous semiconductors have a high concentration of defects, the limited number of electrically active charge carriers causes them to be poor electrical conductors [ 13 ], with electrical resistivity values that are several orders of magnitude higher than the corresponding values in crystalline state.…”

Introductory Chapter: The Prominence of Thin Film Science in Technological Scale

“…• Superconducting thin films, switches, memories [33] • SQUIDS (superconducting quantum interference devices) [34] Mechanics • "Hard" layers (e.g. on drill bits) [35] • Adhesion providers [36] • Friction reduction [37] Introductory Chapter: The Prominence of Thin Film Science in Technological Scale http://dx.doi.org/10.5772/67201 toxicity.…”

Optical and electrical properties of functional materials at the nanoscale

“…Some I-V curves when fitted to the non-interactive model have low chi-square although they have low correlation indexes. These responses may include some contribution of non-interactive sites since, for the non-interactive models, currents follow non-exponential power laws I∼V m , 0 < m < 1 [57]. This I-V response is owing to either an inhomogeneous distribution or a mixing of different trapping sites.…”