Study of Luminescence from GaN:Tb[sup 3+] Powders and Thin Films Deposited by MOVPE and PLD Methods

Abstract

Due to the recent commercial interest in nitride-based optoelectronics and rare-earth emission in nitride materials, the structural and optical characteristics of GaN:Tb 3+ powders and thin films have been investigated in this work. The powder samples were made using a three-step solution method. Pulsed laser deposition ͑PLD͒ and metallorganic vapor phase epitaxy ͑MOVPE͒ methods were utilized for depositing GaN:Tb 3+ films on sapphire substrates. The GaN powders with activator concentrations up to 8 atom % exhibited Tb 3+ luminescence due to the 5 D 3,4 → 7 F j transitions under cathodoluminescence ͑CL͒ as well as under 243 nm photon excitation. Both near-band-edge emission and activator emission have been observed in PLD thin films made from the corresponding GaN:Tb 3+ powders. X-ray diffraction revealed polycrystalline PLD thin films with a preferred growth direction along the c axis, while scanning electron micrographs showed rough film morphology with submicrometer particles. CL emission from Tb 3+ accompanied by near-band-edge emission and defect emissions from the GaN host was observed for the MOVPE films made using tris͑2,2,6,6-tetramethyl-3,5-heptanedionato͒terbium but not films made with tris͑isopropylcyclopentadienyl͒terbium. Despite visible luminescence from Tb 3+ in GaN powders and thin films, no energy transfer from the host to activator ions was observed. This suggests that Tb 3+ is unlikely to fluoresce if used in a GaN-based optoelectronic device.

Dy3+ Emission from GaAlN Powder and Radio-Frequency Sputtered Thin Film

“…The ability to tune band gaps for group III-V nitride alloys from the ultra-violet (UV) range (0.7eV for InN) to beyond the far infrared range (6.2eV for AlN) may allow the possibility of producing a white light solid state source via doping a nitride with a combination of rare earth ions. Visible emission from Eu 3+ , Tb 3+ , Dy 3+ , and Tm 3+ in AlN powders in the red, green, yellow and blue region of the visible spectrum have already been demonstrated in our past work [1,2], as well as luminescence from powders and pulsed-laser deposited thin films of Tb 3+ activated GaN [3].…”

Dy3+ Emission from GaAlN Powder and Radio-Frequency Sputtered Thin Film

“…For this reason, there has been active research in incorporating RE ions into a nitride host for light-emitting devices (3). Eu 3+ , Tb 3+ , Dy 3+ , and Tm 3+ have demonstrated emission in the red, green, yellow and blue region of the visible spectrum in AlN powders, respectively, as we have shown in our past work (4,5), as well as with Tb 3+ -activated GaN powders and pulsed-laser deposited thin films (6). REs have also been used successfully in a GaN host as color emitters in electroluminescent thin films and devices (3,(7)(8)(9).…”

Luminescence Characteristics and Annealing Effect of Tb-Doped AlBNO Films for Inorganic Electroluminescence Devices

“…5 D 4 transition. 10) It suggests that the direct excitation of the Tb process contributes to the luminescence of Tb. This process occurs regardless of the annealing procedure.…”