Negative differential resistance behavior and memory effect in laterally bridged ZnO nanorods grown by hydrothermal method.

A novel memory device based on laterally bridged ZnO nanorods (NRs) in the opposite direction was fabricated by the hydrothermal growth method and characterized. The electrodes were defined by a simple photolithography method. This method has lower cost, simpler process, and higher reliability than the traditional focused ion beam lithography method. For the first time, the negative differential resistance and bistable unipolar resistive switching (RS) behavior in the current-voltage curve was observed at room temperature. The memory device is stable and rewritable; it has an ultra-low current level of about 1 × 10(-13) A in the high resistance state; and it is nonvolatile with an on-off current ratio of up to 1.56 × 10(6). Moreover, its peak-to-valley current ratio of negative differential resistance behavior is greater than 1.76 × 10(2). The negative differential resistance and RS behavior of this device may be related to the boundaries between the opposite bridged ZnO NRs. Specifically, the RS behavior found in ZnO NR devices with a remarkable isolated boundary at the NR/NR interface was discussed for the first time. The memory mechanism of laterally bridged ZnO NR-based devices has not been discussed in the literature yet. In this work, results show that laterally bridged ZnO NR-based devices may have next-generation resistive memories and nanoelectronic applications.

Optical and structural properties of Ga-doped ZnO nanorods.

The high-density single crystalline Ga-doped ZnO nanorods were grown on a glass substrate using the hydrothermal method. The average length and diameter of the nanorods were approximately 2.36 microm and 90 nm, respectively. The Ga-doped ZnO nanorods had hexagonal wurtzite structure and a sharp morphology. The morphology and structure of nanorods were characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy, when the growth temperature of the nanorods was 90 degrees C, which ensured high crystalline quality.

Bending effects of ZnO nanorod metal-semiconductor-metal photodetectors on flexible polyimide substrate.

The authors report the fabrication and I-V characteristics of ZnO nanorod metal-semiconductor-metal photodetectors on flexible polyimide substrate. From field-emission scanning electron microscopy and X-ray diffraction spectrum, ZnO nanorods had a (0002) crystal orientation and a wurtzite hexagonal structure. During the I-V and response measurement, the flexible substrates were measured with (i.e., the radius of curvatures was 0.2 cm) and without bending. From I-V results, the dark current decreased, and the UV-to-visible rejection ratio increased slightly in bending situation. The decreasing tendency of the dark current under bending condition may be attributed to the increase of the Schottky barrier height.