Growth behavior and electrical performance of Ga-doped ZnO nanorod/p-Si heterojunction diodes prepared using a hydrothermal method

Abstract

The incorporation of foreign elements into ZnO nanostructures is of significant interest for tuning the structure and optical and electrical properties in nanoscale optoelectronic devices. In this study, Ga-doped 1-D ZnO nanorods were synthesized using a hydrothermal route, in which the doping content of Ga was varied from 0% to 10%. The pn heterojunction diodes based on the n-type Ga-doped ZnO nanorod/p-type Si substrates were constructed, and the effect of the Ga doping on the morphology, chemical bonding structure, and optical properties of the ZnO nanorods was systematically investigated as well as the diode performance. With increasing Ga content, the average diameter of the ZnO nanorods was increased, whereas the amount of oxygen vacancies was reduced. In addition, the Ga-doped ZnO nanorod/p-Si diodes showed a well-defined rectifying behavior in the I-V characteristics and an improvement in the electrical conductivity (diode performance) by the Ga doping, which was attributed to the increased charge carrier (electron) concentration and the reduced defect states in the nanorods by incorporating Ga. The results suggest that Ga doping is an effective way to tailor the morphology, optical, electronic, and electrical properties of ZnO nanorods for various applications such as field-effect transistors (FETs), light-emitting diodes (LEDs), and laser diodes (LDs).

Recent Progress in Synthesis of Plate-like ZnO and its Applications: A Review

“…However, they only demonstrated to control wire morphology, not to alter the growth direction due to the low-temperature growth process, which is mainly governed by kinetics rather than thermodynamics. Thus, it is important to note that our finding and growth-control mechanism are distinct from results reported previously in solution-based approaches under complex ions or Ga ions assistance 6,[17][18][19] . The ability to control the crystallographic orientation and morphology of anisotropic ZnO wires enables us to achieve the designed physical properties because the presence of spontaneous and piezoelectric polarization strongly influences the behaviors of excitons and electron-hole overlap associated with optical characteristics 1,2 .…”

“…Similar to Ga atoms achieved for the growth of ZnO wires along nonpolar directions, we have also achieved similar control over the growth orientation of ZnO wires by modulating surface energy with Al elements due to the relatively large surface energy lowering (see Supplementary Figure S9b). It has been reported that additional charged complex ions or Ga ions in the growth solution strongly affect the morphology, size, and aspect ratios of ZnO wires 6,[17][18][19] . However, they only demonstrated to control wire morphology, not to alter the growth direction due to the low-temperature growth process, which is mainly governed by kinetics rather than thermodynamics.…”

“…For example, several groups demonstrated control over the growth rate of each crystallographic plane by adding charged complex ions or metal ions, affecting surface properties and nucleation, through solution-based growth [6][7][17][18][19] . They only achieved to obtain wires with controlled aspect ratios and morphology, but the possibility for controlled growth in polar and non-polar orientation was not demonstrated.…”

g-C3N4 decorated ZnO nanorod arrays for enhanced photoelectrocatalytic performance

“…In this regard, one-dimensionally single crystalline ZnO nanorod arrays (NRAs) have attracted 10 extensive attention for application in photochemical and optoelectronic devices, such as photocatalysis [1], solar cells [2], photodetectors [3], diodes [4] due to large surface area, high aspect ratio and short diffusion length. Furthermore, the highly ordered architecture allows light absorption in the axial direction and carrier separation in the radial direction and provides the reduction of carrier recombination before charge separation and direct pathways for efficient charge carrier transport [5].…”

Effects of mid-gap defects and barrier interface reactions on tunneling behaviors of ZnO-i-Si heterojunctions

“…ZnO is a multifunctional wide bandgap semiconductor and its compatibility with monolithic device fabrications for integration with Si is of great general interest. 1,14,15 The related devices reported in literature involved largely a buffer layer, such as Gd 2 12,18 Post-deposition annealing, meanwhile, is a common practice in reducing various detrimental effects, such as interfacial imperfections, domain or grain boundaries 26 and point defect which are often responsible for the presence of mid-gap states. The efforts reported here were intended to understand how processing conditions would affect the tunnelling characteristics and thus the device performance, especially in the origins of unwelcome leakage paths and the means to avoid or to exploit them.…”