Unipolar resistive switching and tunneling oscillations in isolated Si–SiO_xcore–shell nanostructure

Abstract

Unipolar resistive switching (URS) is observed in isolated Si-SiO core-shell nanostructures. I-V characteristics recorded by a conductive atomic force microscope tip show SET and RESET processes with self compliance behavior. Hopping of carriers through defect states in the high resistance state (HRS) and space charge limited conduction in the low resistance state (LRS) are found to be the dominant carrier transport mechanisms in Si-SiO core-shell nanostructures. URS between LRS and HRS may be attributed to the transition between hydrogen bridge (Si-H-Si) and hydrogen doublet (Si-HH-Si) defects. During RESET process, charge carriers tunnel through the nanostructure giving rise to oscillatory conduction.

Electrical transport through array of electrochemically etched silicon nanorods

“…According to hydrogenated defect switching, electrochemical reaction results in transition of non‐conductive hydrogen doublet (Si–HH–Si) defect states to conductive hydrogen bridge (Si–H–Si) defect states, through proton (H + ) transfer . Thus, significant decrease in localized non‐conductive defect states concentration along with metal diffusion results in switching from high resistance state to low resistance state, as we have discussed in our previous work . As a result of the decreasing barrier width, the tunneling of carrier takes place through the oxide matrix at high electric field.…”

“…Similar high resistive materials when sandwiched between metal electrodes exhibit resistive switching (RS) phenomenon, resulting in non‐volatile resistive random access memory (RRAM) devices . Recently, we have observed RS in single Si‐SiO x core‐shell nanostructure . Nearly symmetric and asymmetric diode‐like rectifying I–V characteristics of metal and nanocrystalline Si junctions have been studied and reported .…”

Origin of photo-enhanced hysteretic electrical conductance in nanostructured silicon-based heterojunction

“…However, efficiency of electroluminescence from these devices were not high enough for commercial applications. This is mainly due to the growth of a wide band gap non-stoichiometric native silicon oxide layer as a shell material around the nanocrystalline core [3,8,9]. Due to the wider band gap of the oxide shell around the Si nanocrystalline core, stronger confinement of photogenerated carriers favours efficient radiative recombination leading to brighter PL [8,10].…”

“…Whereas, this oxide layer becomes detrimental to electroluminescent and photovoltaic devices by hindering the injection and extraction of charge carriers from nanocrystalline core respectively [6,11]. The exact transport mechanism through SiNCs is still elusive as the nonstoichiometric oxide layer and the oxide related traps play a crucial role during charge transport through it [3,9,[12][13][14]. There are few mechanisms reported in literature revealing the bulk as well as interface/surface states dominated transport process but none of them is conclusive [15][16][17].…”

“…In previously reported studies on charge transport in Si nanostructures, defect/traps states have been found to play a crucial role [3,4,9,26]. Hence, we have tried to explain the transport of charge carriers using a microscopic description of the trapping and detrapping of the photo-excited carriers.…”