Influence of Er and O doses in Er-related emission in Al 0.70 Ga 0.30 As:Er
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Influence of Er and O doses in Er-related emission in Al0.70Ga0.30As:Er Shin-ichiro Uekusa and Tomoyuki Arai Department of Electrical and Engineering, Meiji University, 1-1-1 Higashi-mita, Tama-ku, Kawasaki, Kanagawa, Japan ABSTRACT Er ions with doses ranging from 1x1013 cm-2 to 1x1015 cm-2 were implanted into Al0.70Ga0.30As on GaAs substrates. at 800 oC. Photoluminescence (PL) intensity of Er-related emission around 1.54 µm was enhanced by co-implanted oxygen (O). The optimum dose of Er ion was 1x1014 cm-2 and O ion was 1x1015 cm-2, respectively. Furthermore, from the temperature dependence of the PL intensity of sample implanted with the optimum dose, we estimated the values of E1, E2 , and E 3 , the activation energies in order to investigate the rapid thermal quenching of Er ion in Al0.70Ga0.30As. We found that PL intensity of Er-related emission, in addition to O dose, was enhanced approximately twenty two times at room te mperature. And from the temperature dependence of the lifetime of the optimum dose of Er and O, the value 245meV of E A , the activation energy for the decrease of the lifetime, was nearly equal to the value 235meV of E3. Based on the result, the decrease of the lifetime confirms that the radiative efficiency is lower; therefore, we propose that rapid thermal quenching occurs at temperatures above 200 K due to the decrease of the radiative efficiency. INTRODUCTION Rare-earth(RE) impurities in Ⅲ-Ⅴ semiconduc tors have attracted much attention due to their potential applications in new emitting devices and based on the internal emission from the 4f levels of the impurity. The intra-4f shell transitions cause sharp and temperature-stable luminescence because of shielding by outer electronic shells. [1,2] Therefore the research on the optical devices, which involves RE element, has been advanced. Er is attractive for obtaining light emitting device in silica-fiber-based optical communication systems. As a matter of fact, the luminescence from Er3+ ion occurs at a wavelength of 1.54 µm [3,4], which corresponds to the minimum absorption of silica-based optical fibers. However Er-doped semiconductors have problems such as low energy transition efficiency from the host semiconductor to the intra-4f-shell of Er3+ ions. Therefore it is important that we understand the mechanism of the energy transition. We have
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previously reported photoluminescence (PL) properties for the dependence of the composition ratio (x) in Alx Ga1-x As, and the influence of light elements (O, N, and C) on the low dosage 1x1013cm-2 of Er. [4] In this work, we studied the influence of O on Er3+ -related emission with the high Er doses ranging from 1x1014cm-2 to 1x1015cm-2. EXPERIMENT Er 3+ ion of 1 MeV were implanted into undoped Al0.70Ga0.30As (100) grown by molecular beam epitaxy (MBE) with doses ranging from 1x1013 cm-2 to 1x1015cm-2 at room temperature. The projected range (Rp) and straggling (∆Rp) for implant profile were calculated by materials computer program (TRIM) to be 205.7 and 58.4nm, respectively. O ion w
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