Near band edge emission of MBE grown ZnO epilayers: identification of donor impurities and O₂ annealing effects

Abstract

Photoluminescence (PL) and selective photoluminescence (SPL) experiments have been carried out to analyse the near band edge emission (NBE) spectra of unintentionally doped ZnO epilayers. It is shown that the different NBE transitions involve donor centres only. The lines can be divided into two groups. Those lying on the low energy side consist of recombinations of neutral-donor bound exciton complexes, while those lying just below the A free excitonic emission correspond to donor-to-valence band transitions. One of the donors is identified as indium. The emission energy of the In-donor bound exciton, the spectra of the bound exciton excited states, the In-related D 0 h transition energy, and the electronic spectrum of the In-donor are established. The binding energies of another three donor centres are evaluated. The occurrence of two of these centres is shown to depend on the stoechiometry, as revealed by annealing experiments in an O 2 atmosphere.

Photostable Zn2SnO4 Nanowire Transistors for Transparent Displays

“…11,14,15 Although the near-IR emission around 760 nm is sometimes thought to be caused mainly by interstitial zinc, 16 it is more likely to be the second peak of UV emission caused by transitions due to SiÀOÀZn bonds. 12,17,18 The XRD measurements for SnO 2 nanowires (Figure 2b) show main peaks at (110), (101), and (211), and the SnO 2 crystalline structure is tetragonal rutile with lattice constants a = 4.737 Å and c = 3.186 Å (ICDD No. 88-0287).…”

Effects of annealing temperature on excitonic emissions from Na-implanted ZnO nanorods

“…However, later studies indicated that the I 9 line is actually from excitons bound to In-donors [18][19][20].…”

Effect of annealing on the morphology and optoelectrical characteristics of ZnO thin films grown by plasma-assisted molecular beam epitaxy

“…One of these methods is postgrowth annealing. Annealing has been employed widely for ZnO grown by sputtering, 6,7 molecular beam epitaxy (MBE), 8,9 atomic layer epitaxy, 10 and to ZnO substrates for homo-epitaxial growth 11 to improve the crystalline quality and optical and electrical characteristics for further applications. It has also been employed during the growth process itself to improve the quality of the epilayers.…”