A class of nanomaterials that display these characteristics is amorphous semiconductors [1]. Generally, amorphous semiconducting nanostructures display some advantageous electrical characteristics compared with their crystalline counterparts. In particular, due to their disordered structure,

amorphous materials typically have a high density of localized defect states, resulting in significant charge trapping and much lower leakage current [2]. Moreover, amorphous nanomaterials can be produced at relatively low temperatures, while a lower strain is expected between the embedded nanoparticles and the matrix due to their flexible amorphous structure [3]. In addition, very recent works have demonstrated that some amorphous or polycrystalline nitrides, like CuN, AlN, and NiN, #check details randurls[1|1|,|CHEM1|]# exhibit resistive switching behavior capable for fabricating resistance-switching random access memory devices [4–7]. However, the research for switching resistive materials had been focused almost only on metal oxides, e.g., TiO2[8, 9], NiO [10, 11], ZnO [12], and Ta2O5[13–16], as their electrical properties are well known and their preparation methods are relatively easy and well established. On the contrary, metal nitrides, even though they exhibit intriguing electrical properties, remain largely unexplored in this field. Low-power

memristive behavior with outstanding endurance has been already demonstrated in tantalum oxide QNZ in vivo [13–15], alongside with efforts to maximize its performance with nitrogen doping [16]. A promising material in this point of view is amorphous tantalum nitride (a-TaN x ). Tantalum nitride is proved to be a mechanically hard and a chemically inert material, combining both high thermal stability and low temperature coefficient of resistance [17, 18]. TaN x appears

with many crystalline phases that are well studied [19, 20]. For example, the metallic TaN may have potential applications as Cu diffusion barriers [21], enough thin film resistors [22], and superconducting single-photon detectors [23], while nitrogen-rich Ta3N5 is used as photocatalytic material for water splitting [24, 25]. On the other hand, the amorphous phase (a-TaN x ), which is the most common phase of the as-prepared TaN x at relatively low temperatures [26–28], has received very low attention. Early electrical studies on a-TaN x films by Chang et al. showed that there was increasing resistivity of films, as the nitrogen concentration in the gas environment increased [29], while Kim et al. [30] indicated that a-TaN x could prevent copper diffusion more effectively than the crystallized Ta2N film by eliminating grain boundaries. It is well known for 1-D and 2-D nanostructures, i.e.