Structural, morphological, optical and electrical properties of Schottky diodes based on CBD deposited ZnO:Cu nanorods

Abstract

Undoped and copper doped zinc oxide (ZnO) nanorods have been synthesized by a simple chemical bath deposition (CBD) method at a temperature of 90 °C. Structural, morphological, optical and electrical properties of the synthesized ZnO nanorods were found to be dependent on the Cu doping percentage. X-ray diffraction (XRD) patterns revealed strong diffraction peaks of hexagonal wurtzite of ZnO, and no impurity phases from metallic zinc or copper. Scanning electron microscopy (SEM) images showed changes in diameter and shape of nanorods, where by those doped with 2 at.% and 3 at.% aggregated and became compact. Selected area electron diffraction (SAED) patterns indicates high quality, single crystalline wurtzite structure ZnO and intensities of bright spots varied with copper doping concentration. UV-visible absorption peaks of ZnO red shifted with increasing copper doping concentration. Raman studies demonstrated among others, strong and sharp E 2 (low) and E 2 (high) optical phonon peaks confirming crystal structure of ZnO. Current-voltage measurements based on the gold/ZnO nanorods/ITO showed good rectifying behavior of the Schottky diode. The predicted Schottky barrier height of 0.60 eV was obtained which is not far from the theoretical Schottky-Mott value of 0.80 eV.

Effect of Sm doping ZnO nanorods on structural optical and electrical properties of Schottky diodes prepared by chemical bath deposition

“…9 (A) and (B) the rectification behavior is positively improved when doping with Sm (1.5 at.%) at applied voltage ±1 V. The difference between forward and revers current at 1.5 at.% is almost two and half orders of magnitude compared to undoped samples. Our results for undoped samples are similar to previously reported on ZnO Schottky diodes prepared using the CBD technique [63]. However, for Sm doped ZnO nanorods at 4.0 and 5.5 at.% (not shown) there was no rectification.…”

“…The deviation of these values from the theoretically calculated one (difference between Pd work function and ZnO electron affinity) could be due to some factors. For examples, non-homogeneous barrier formation, poor contact between Pd/ZnO [63], deviation from the linearity of I-V characteristic and Sm doping could probably cause this deviation.…”

Chemical Bath Deposition of ZnO Nanowires Using Copper Nitrate as an Additive for Compensating Doping

“…A couple of previous investigations have reported some experimental evidence of the incorporation of Cu into ZnO NWs and nanoparticles grown by CBD by generally adding copper nitrate (Cu(NO 3 ) 2 ) in the bath. [22][23][24][25][26][27] Other investigations have reported the use of copper chloride, copper acetate, and copper sulfate. [28][29][30] However, the required conditions in the chemical bath for inducing the Cu incorporation and the nature of the related mechanisms have not been described in detail.…”

Effects of surface morphology on the optical and electrical properties of Schottky diodes of CBD deposited ZnO nanostructures

“…Prior to deposition, the substrates were cleaned by sonicating in deionized water, acetone, ethanol for 5 min each, and then dried using N2 gas. The detailed procedures for the preparation of the gel, deposition of the seed layer and growth of ZnO nanorods are as described in our previous work [8]. However, in this study the nanostructure growth was achieved by suspending substrates with the seeded surface facing: downward (Sample 1), vertically (Sample 2) and up (Sample 3) as shown in Fig 1 (a).…”