Luminescence Properties of Eu ion-implanted GaN

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Y5.7.1

Luminescence Properties of Eu ion-implanted GaN Shin-ichiro Uekusa and Isao Tanaka Department of Electrical and Electronic Engineering, Meiji University, 1-1-1 Higashi-mita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan ABSTRACT The Eu ion was implanted at an energy of 300keV with a dose of 1 × 1015cm-2 at room temperature. Photoluminescence (PL) and PL lifetime were characterized and studied on thermal quenching process. We calculated the activation energy (E1) of temperature dependent PL and the value of E1 was 5.68meV. E1 was affected the luminescence intensity in the temperature range from 15K to 70K. The activation energy (Ea) of PL lifetime was calculated and the value of Ea was 8.5meV. The non-radiative recombination in the transition from the 5D0 to 7F2 of Eu was dominated in the temperature range from 15K to 100K. We found that the thermal quenching occurred in both the electron emission from RE-trap and the non-radiative recombination in the transition on Eu in the temperature range from 15K to 70K. INTRODUCTION Rare-earth (RE)-doped semiconductors are of interest in view of the potential application to optoelectronic devices because of their sharp, temperature-stable emission originating from intra-4f-shell transition of the RE metal [1-5]. In particular, the Eu ion shows luminescence of about 600nm by the transition from the 5D0 to 7FJ (J=0~4), it is expected as a element which emits red light emission in red-green-blue (RGB) colors [6-7]. Gallium nitride (GaN) is very useful host material because it has a wide band gap and potentially improves the luminescence properties of rare earth ions. Therefore, RE-doped group-III nitrides optoelectronic devices may be candidate for white light sources to replace fluorescent lighting. For the RE-doped semiconductor, it is important to resolve problems such as poor luminescence intensity and rapid thermal quenching of the RE-related emission of energy transition from the host semiconductor to the intra-4f-shell of Rare-earth ions. Therefore, luminescence is weak and difficult to use at room temperature as a practical light source. The purpose of this study is to investigate the luminescence properties of Eu3+-related emission in GaN. We implanted Eu into Si-doped epitaxial GaN layer (GaN:Eu) grown on sapphire substrate and studied Photoluminescence (PL) and its lifetime. We also calculated the activation energy of thermal quenching process from temperature dependent PL and PL lifetime.

Y5.7.2

EXPERIMENTAL DETAILS

PL Intensity (arb.units)

The Eu ion was implanted at an energy of 1MeV with a dose of 1x1013cm-2 at room temperature. The wafer used in this work was a Si-doped (n=9.8x1017cm-3) epitaxial n-GaN layer grown on sapphire substrate. After the ion implantation, these samples were thermally annealed at temperatures ranging from 1000 to 1400ºC and at times ranging from 10 to 60 minutes by rapid thermal annealing. The heating and cooling rates were 5ºC/s. Before annealing, the apparatus was pumped down to a base pressure of 5.0x10-6 Torr before an atmo