Wahl U, Amorim L M, Augustyns V, Costa A, David-Bosne E, Lima T A L, Lippertz G, Correia J G, da Silva M R, Kappers M J, Temst K, Vantomme A, Pereira L M C
Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela, Portugal.
KU Leuven, Instituut voor Kern- en Stralingsfysica, 3001 Leuven, Belgium.
Phys Rev Lett. 2017 Mar 3;118(9):095501. doi: 10.1103/PhysRevLett.118.095501. Epub 2017 Mar 1.
Radioactive ^{27}Mg (t_{1/2}=9.5 min) was implanted into GaN of different doping types at CERN's ISOLDE facility and its lattice site determined via β^{-} emission channeling. Following implantations between room temperature and 800 °C, the majority of ^{27}Mg occupies the substitutional Ga sites; however, below 350 °C significant fractions were also found on interstitial positions ∼0.6 Å from ideal octahedral sites. The interstitial fraction of Mg was correlated with the GaN doping character, being highest (up to 31%) in samples doped p type with 2×10^{19} cm^{-3} stable Mg during epilayer growth, and lowest in Si-doped n-GaN, thus giving direct evidence for the amphoteric character of Mg. Implanting above 350 °C converts interstitial ^{27}Mg to substitutional Ga sites, which allows estimating the activation energy for migration of interstitial Mg as between 1.3 and 2.0 eV.
放射性(^{27}Mg)（半衰期(t_{1/2}=9.5)分钟）在欧洲核子研究中心的ISOLDE设施中被注入到不同掺杂类型的氮化镓（GaN）中，并通过(\beta^-)发射沟道确定其晶格位置。在室温至800°C之间进行注入后，大部分(^{27}Mg)占据替代镓（Ga）位点；然而，在350°C以下，也发现有相当一部分位于距理想八面体位置约0.6 Å的间隙位置。镁的间隙分数与氮化镓的掺杂特性相关，在生长外延层期间以(2×10^{19}\ cm^{-3})稳定镁进行p型掺杂的样品中最高（高达31%），在硅掺杂的n型氮化镓中最低，从而直接证明了镁的两性特性。在350°C以上进行注入会将间隙(^{27}Mg)转化为替代Ga位点，这使得能够估计间隙镁迁移的活化能在1.3至2.0电子伏特之间。
