Photoluminescence of Europium in ZnO and ZnMgO thin films grown by Molecular Beam Epitaxy

Eu3+ Luminescence Enhancement via Bandgap Engineering of Zn1–xMgxO:Eu Epitaxial Thin Films

“…In our previous investigation, we found that the Eu luminescence efficiency is an order of magnitude higher in Eu-doped ZnMgO with around 10% fractional Mg content in comparison to Eu-doped ZnO matrix and that thermal annealing in oxygen ambient stimulates the emission from Eu 3+ in ZnO. 30 Other studies in nitride semiconductors have shown that the presence of oxygen and Mg in GaN:Eu greatly enhances the efficiency of the red emission of Eu 3+ ions. 39 This observation makes ZnMgO:Eu a natural material choice for efficient red emission.…”

“…The high proportion of Eu 3+ in the O2.5 sample is evidence that the oxygen-rich environment promotes the formation of trivalent europium in ZnMgO alloys. 30 Figure 3a , where the standard "c" lattice parameter for unstrained wurtzite ZnO,c 0 = 5.205 Å. 46,47 Figure 3b presents the Zn 1−x Mg x O:Eu thin films' c-lattice parameters as a function of the fractional Mg content.…”

“…Oxide-wide-bandgap semiconductors are ideal materials for doping RE ions due to their availability at low cost, ease of synthesis, chemical stability, and, above all, due to the tunability of electrical and optical properties. ,, Among the semiconducting oxide host materials for REs, ZnO is a well-investigated and widely accepted semiconductor with its ∼3.37 eV bandgap energy at room temperature and exciton binding energy of 60 meV, favorable for laser and other optoelectronic applications mainly in the ultraviolet regime. For the past few decades, the properties of europium (Eu) doped ZnO have been studied extensively. – Eu-doped ZnO thin films and nanopowders have been shown as potential candidates for gas sensing, photocatalytic activity, thermal sensing, bioimaging, antibacterial applications, etc. – Besides, depending on the synthesis routes, europium doped in ZnO coexists in its Eu 2+ and Eu 3+ ionic states and is very promising in its 3+ state to produce red light via intra-4f transitions. , The structural characteristics of Eu-doped ZnO thin films, nanostructures, and ZnO-based glasses have been investigated in relation to their excitation–emission mechanisms and the host-to-dopant energy transfer processes. – Electroluminescence via hot-hole or hot-electron impact excitation is another functional application of Eu-doped ZnO. , However, ZnO reveals defect-related visible emission in the green–yellow–orange region, which depends on the synthesis methods and other parameters such as chemical reagents, the temperature of synthesis, post-synthesis annealing treatment, etc., thus questioning the reproducibility of the emission in the visible range. – An advantage of the defect states is that they can also act as a pathway for energy transfer to intentional dopants, promoting desirable emission from the dopants. , Enhanced emission from Eu 3+ states is observed in ZnO when energy transfer occurs mediated via defect centers , or directly via the transfer of exciton recombination energy to Eu ions …”

Preparation of ZnMgO/ZnO heterojunction by magnetron sputtering method

“…At present, ZnMgO/ZnO heterostructures are mainly prepared by MBE [5][6][7] , PLD or MOCVD techniques, and S. Krishnamoorthy [8] et al used PLD epitaxial growth technique to grow ZnMgO/ZnO/ZnMgO double-barrier heterojunction barrier heterojunctions on sapphire c-plane substrates and observed the resonant tunneling effect. Some domestic units have also started to investigate ZnMgO/ZnO heterojunctions.…”

Combined Effects of Ultraviolet Irradiation and Magnetic Field on the Properties of Dip-coated ZnO thin films

“…To date, various physical and chemical preparation techniques have been used to synthesize ZnO thin films, including chemical vapor deposition [14], pulsed-laser deposition (PLD) [15], glancing angle deposition (GLAD) technique [16], sputtering [17], spray pyrolysis technique [18], electron beam evaporation [19], molecular beam epitaxy [20] and sol-gel deposition [21]. Among these deposition methods, sol-gel dip coating is a versatile and inexpensive method for fabricating thin films [22].…”