@article{5be9440798f9432eb99076bdc086a8e0,
title = "Migration energy barriers for the surface and bulk of self-assembly ZnO nanorods",
abstract = "Post-annealing treatment is a necessary process to create/eliminate/repair defects in self–assembly (SA) metal oxide by providing enough thermal energy to the O atoms to overcome the migration energy barrier in ZnO. The height of migration energy barrier is dependent on the depth from the surface, which is hard to be estimated by theoretical calculations, as well as the optical analyses. SA ZnO nanorods (ZNRs) have high surface-to-volume ratio to provide complete picture between the optical and surface properties obtained by photoluminescence (PL) and ultraviolet/X-ray photoemission spectroscopy (UPS/XPS), which is used to investigate the evolution of structure and chemical states of the surface layers to reveal mutual agreement on all observations in PL, XPS, and UPS. We demonstrate variation of the surface structure of SA-ZNRs by scanning over a range of annealing temperatures and time to regulate the structure variation of SA-ZNRs, and their optical analyses agrees well with PL, XPS and UPS, which indicates the dependence of migration energy barriers on the depth from the surface of ZNR. The results reveal the well ZNRs formed at 570 °C and the further oxidation process and the formation of hydroperoxide on the Zn-rich surface of ZNRs at 640 °C.",
author = "Chang, {Feng Ming} and Wu, {Zhong Zhe} and Huang, {Jing Heng} and Chen, {Wei Ting} and Sanjaya Brahma and Lo, {Kuang Yao}",
note = "Funding Information: Funding: This work was supported by Ministry of Science and Technology of the Republic of China, Taiwan (MOST 107-2112-M-006-021) Funding Information: This work was supported by Ministry of Science and Technology of the Republic of China, Taiwan (MOST107-2lit2-M-006-021). Funding Information: with certain depth which determines the corresponding activation energy. The amplitude of activation 4. Conclusions energy is certainly correlated to the depth of ZNRs. Moreover, the surface layers of SA-ZNRs were not only rAebstorvuec tuinrsepdebcutitoanlss ooncr ePaLte, aXnPoSt,h aerndse tUoPfSd efofirc ieanncnieeaslaedcc oSrAd-iZngNtRosthweitahn nsecaalninnginegn vteirmonpmereantutrief tphreovanidnee atlhineg qpuraoncetistsatliavset s alonnaglyesretsi moen atthhei grheesrtrtuemctupreer aatunrde. aTnhneihfuilratthioenr aopfp ldiceaftiicoiennbciaesse.d Aosn tthhee kdnisocwrelpedangceyabonou PtLthaenedvXolPuSt,i othneo sfttrhuectmurige reavtioolnuteionnerigny dbeaprtrhie crsano nbeZiNnRspseucrtefadc eanwdo ruelvdeiaml apcrtoivvaettihone feanberrigcaietsionwoitfhZ tNheR sdeenpseonrdse[n29ce]. Tofh edseepnthsi.t iTvhitey orefsZtrNuRctsuirse starnodngtlhyec oerlirmeliantaetdiown itohf thdeefqicuiaenlictyieas nodf cShAe-mZNicaRlss otactceusro ifnZ tNheRlsimsuitrefdac de.epTothu inf dtheers atannndeatlhinegsutermfacpeermatiugrrea tiiso nlimeniteerdgywbitahrirnie4rs70o–f5Z4N0 °RCs weveelnl, tahtelosunrgfearc eacnonnefaigliunrga ttiiomneo. fIZt Nis Rosbsvhioouusld thbeatcothnetr oanllnedeawlienlgl btyrepartmeceisnetpwositth-anspneecailfiincg tteomdpeevrealtoupreZ NcaRn soennlsyo rrseswtriuthcthuirgeh thseen SsiAti-vZitNy.Rs with certain depth which determines the corresponding activation energy. The amplitude of activation energy is certainly correlated to the depth of ZNRs. Moreover, the surface layers of SA-ZNRs were not only restructured but also create another set of deficiencies XPS and UPS experiments. J.-H.H. performed PL analyses. W.-T.C. assisted the model building. S.B. analyzed PL according to the annealing environment if the annealing process lasts longer time at higher temperature. The further application based on the knowledge about the evolution of the migration Funding: This work was supported by Ministry of Science and Technology of the Republic of China, Taiwan (MOSTenergy b107-2112-M-006-021)arriers on ZNR surface would improve the fabrication of ZNR sensors [29]. The sensitivity of ZNRs is strongly correlated with the quality and chemical states of ZNRs surface. To understand othf eC hsiunraf,aTcaei wmaing,rfaotriofinn aennceiarlglyy sbuaprprioerrtsinog.f TZhNisRwsowrkelwl,atshael ssousrufpacpeorctoednfbigyuthraetAiodnv aonfcZedNORpstosheloeuctlrdonbice controlled well by precise post-annealing to develop ZNR sensors with high sensitivity. Conflicts of Interest: The authors declare no conflicts of interest. Author Contributions: F.-M.C. prepared samples, and preformed XPS and UPS experiments. Z.-Z.W. performed XPS and UPS experiments. J.-H.H. performed PL analyses. W.-T.C. assisted the model building. S.B. analyzed PL and physics of ZNRs. K.Y.L. wrote the main manuscript and initiated and supervised the research. Publisher Copyright: {\textcopyright} 2018 by the authors. Licensee MDPI, Basel, Switzerland.",
year = "2018",
month = oct,
day = "9",
doi = "10.3390/nano8100811",
language = "English",
volume = "8",
journal = "Nanomaterials",
issn = "2079-4991",
publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",
number = "10",
}