Correlation between reflectance and photoluminescent properties of al-rich ZnO nano-structures

Abstract

Al rich zinc oxide nano-structured films were synthesized using spin coating sol-gel technique. The films were annealed in oxygen ambient in the temperature range of 200-700°C. The structural, optical, and photoluminescence (PL) properties of the films were studied at various annealing temperatures using X-ray diffraction spectroscopy, field emission scanning electron microscopy, photoluminescence emission spectra measurement, and Raman and UV-Vis spectroscopy. The optical band gap was found to decrease with the increase of the annealing temperature following the Gauss Amp function due to the confinement of the exciton. The PL peak intensity in the near band region (INBE) was found to increase with the increase of the annealing temperature up to 600°C, then to decrease fast to a lower value for the annealing temperature of 700°C due to crystalline quality. The Raman peak of E2 (low) was red shifted from 118 cm -1 to 126 cm -1 with the increase of the annealing temperature. The intensity of the second order phonon (TA+LO) at 674 cm -1 was found to decrease with the increase of the annealing temperature. The normalized values of the reflectance and the PL intensity in the NBE region were highest for the annealing temperature of 600°C. A special correlation was found between the reflectance at λ = 1000 nm and the normalized PL intensity in the green region due to scattering due to presence of grains.

Investigation on the Deposition of an AlN-ZnO/ZnO/AlN-ZnO Double Heterojunction Structure Using Radio Frequency Magnetron Cosputtering Technology

“…Figure 8a,b give a deconvolution on this UV light luminescence that emerged from the single ZnO film and AlN-ZnO/ZnO structure, respectively, to extract the reason for the changes of peak position and the wide FWHM of this short-wavelength emission. As quoted from previous reports [32][33][34], the short-wavelength luminescence emitted from the undoped ZnO film directly deposited onto the substrate (Figure 8a) was deconvoluted into two curves with peaks at 382 and 391 nm, which were in turn characterized as the recombination of the free exciton and bound exciton associated with the donor and/or acceptor impurities, respectively. Compared to the undoped ZnO film directly deposited onto the substrate, the visible wavelength luminescence associated with the DL transitions in the ZnO film almost was absent in the PL spectrum of the undoped ZnO film deposited onto the AlN-ZnO buffer layer, and thereby only one peak was measured around the ultraviolet wavelength.…”

Zinc Aluminum Oxide Encapsulation Layers for Perovskite Solar Cells Deposited Using Spatial Atomic Layer Deposition

“…This results in a film with two distinct phases, Al 2 O 3 and ZnO, which is consistent with the increased O─H signal observed for this film in Figure 2c. [50] Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of Al 2 O 3 and Zn-AlO x films deposited on silicon substrates using 120 substrate oscillations are shown in Figure 3a-e, confirming the smooth, pinhole-and crack-free nature of the films, which is well suited for TFE. From Figure 3a, some randomly distributed particles on the surface of the Al 2 O 3 film can be observed, which could result from gradual powder formation on the underside of the AP-SALD reactor head.…”

“…This results in a film with two distinct phases, Al 2 O 3 and ZnO, which is consistent with the increased O─H signal observed for this film in Figure 2c. [ 50 ]…”

Crystal Al-Doped ZnO Thin-Film Preparation by Sputtering Deposition using a Mixed-Powder Target

“…The photographs of the deposited films show that their appearance changed from transparent to blackish-brown as the deposition time increased. It is known that ZnO thin films prepared by conventional sputtering deposition using a bulk target turn blackish-brown as the ratio of metallic Zn in the film increases (38) . In this experiment, almost 100% Ar gas was used for the deposition.…”