Impact of Mg level on lattice relaxation in a p-AlGaN hole source layer and attempting excimer laser annealing on p-AlGaN HSL of UVB emitters

M. Ajmal Khan, Juan Paolo Bermundo, Yasuaki Ishikawa, Hiroshi Ikenoue, Sachie Fujikawa, Eriko Matsuura, Yukio Kashima, Noritoshi Maeda, Masafumi Jo, Hideki Hirayama

研究成果: ジャーナルへの寄稿学術誌査読

17 被引用数 (Scopus)


Mg-doped p-type semiconducting aluminium-gallium-nitride hole source layer (p-AlGaN HSL) materials are quite promising as a source of hole 'p' carriers for the ultraviolet-B (UVB) light-emitting diodes (LEDs) and laser diodes (LDs). However, the p-AlGaN HSL has a central issue of low hole injection due to poor activation of Mg atoms, and the presence of unwanted impurity contamination and the existence of a localized coherent state. Therefore, first the impact of the Mg level on the crystallinity, Al composition and relaxation conditions in the p-AlGaN HSL were studied. An increasing trend in the lattice-relaxation ratios with increasing Mg concentrations in the p-AlGaN HSL were observed. Ultimately, a 40%-60% relaxed and 1.4 μm thick p-AlGaN HSL structure with total threading dislocation densities (total-TDDs) of approximately ∼8-9 × 108 cm-2 was achieved, which almost matches our previous design of a 4 μm thick and 50% relaxed n-AlGaN electron source layer (ESL) with total-TDDs of approximately ∼7-8 × 108 cm-2. Subsequently, structurally a symmetric p-n junction for UVB emitters was accomplished. Finally, the influence of excimer laser annealing (ELA) on the activation of Mg concentration and on suppression of unwanted impurities as well as on the annihilation of the localized energy state in the p-AlGaN HSL were thoroughly investigated. ELA treatment suggested a reduced Ga-N bonding ratio and increased Ga-O, as well as Ga-Ga bonding ratios in the p-AlGaN HSL. After ELA treatment the localized coherent state was suppressed and, ultimately, the photoluminescence emission efficiency as well as conductivity were drastically improved in the p-AlGaN HSL. By using lightly polarized p-AlGaN HSL assisted by ELA treatment, quite low resistivity in p-type AlGaN HSL at room temperature (hole concentration is ∼2.6 × 1016 cm-3, the hole mobility is ∼9.6 cm2 V1 s-1 and the resistivity is ∼24.39 Ω. cm) were reported. ELA treatment has great potential for localized activation of p-AlGaN HSL as well as n- and p-electrodes on n-AlGaN and p-AlGaN contact layers during the flip-chip (FC) process in low operating UVB emitters, including UVB lasers.

出版ステータス出版済み - 1月 29 2021

!!!All Science Journal Classification (ASJC) codes

  • バイオエンジニアリング
  • 化学一般
  • 材料科学一般
  • 材料力学
  • 機械工学
  • 電子工学および電気工学


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