Optical signature of Mg-doped GaN: Transfer processes
Optical signature of Mg-doped GaN: Transfer processes
复制标题
DOI：
10.1103/physrevb.86.075207
复制
发表时间：
2012-08
影响因子：
3.7
通讯作者：
G. Callsen;M. R. Wagner;T. Kure;J. Reparaz;M. Bügler;J. Brunnmeier;C. Nenstiel;A. Hoffmann;M. Hoffmann;J. Tweedie;Z. Bryan;S. Aygun;R. Kirste;R. Collazo;Z. Sitar
中科院分区：
文献类型：
--
作者：
G. Callsen;M. R. Wagner;T. Kure;J. Reparaz;M. Bügler;J. Brunnmeier;C. Nenstiel;A. Hoffmann;M. Hoffmann;J. Tweedie;Z. Bryan;S. Aygun;R. Kirste;R. Collazo;Z. Sitar
在高质量的金属有机化学气相沉积GaN薄膜中掺杂Mg，其光致发光光谱和光致发光激发光谱都有明显的痕迹。我们分析了在蓝宝石衬底上生长的GaN:Mg，并确定了两个与Mg相关的受体状态，一个额外的受体状态和三个供体状态，它们参与了GaN:Mg中3.26-3.29 eV的供体-受体对带跃迁。本文通过光致发光激发光谱结合温度依赖性光致发光测量来确定供体-受体对带激发通道，从而直接确定供体和受体的结合、定位和活化能，并将其置于基于Haynes规则的更广泛的背景下。此外，我们还分析了受体和供体结合激子的光致发光信号的双指数衰减动力学。由于所有观察到的寿命都与供体和受体相关束缚激子的定位能量有关，因此可以排除缺陷和复杂束缚激子作为它们的来源。对氮化镓带边缘附近的激子转移过程的详细分析表明，激子通过自由和束缚激子通道激发，但也通过激发态激发，如最深层的局域Mg相关受体结合激子。对于两种Mg受体态，我们确定了结合能为164±5和195±5 meV，这与最近的密度泛函理论结果很好地吻合。基于对光致发光和激发光谱的分析，这一观察证实并量化了GaN中受体状态的一般双重性质。
Mg doping of high quality, metal organic chemical vapor deposition grown GaN films results in distinct traces in their photoluminescence and photoluminescence excitation spectra. We analyze GaN:Mg grown on sapphire substrates and identify two Mg related acceptor states, one additional acceptor state and three donor states that are involved in the donor-acceptor pair band transitions situated at 3.26–3.29 eV in GaN:Mg. The presented determination of the donor-acceptor pair band excitation channels by photoluminescence excitation spectroscopy in conjunction with temperature-dependent photoluminescence measurements results in a direct determination of the donor and acceptor binding, localization, and activation energies, which is put into a broader context based on Haynes’s rule. Furthermore, we analyze the biexponential decay dynamics of the photoluminescence signal of the acceptor and donor bound excitons. As all observed lifetimes scale with the localization energy of the donor and acceptor related bound excitons, defect and complex bound excitons can be excluded as their origin. Detailed analysis of the exciton transfer processes in the close energetic vicinity of the GaN band edge reveals excitation via free and bound excitonic channels but also via an excited state as resolved for the deepest localized Mg related acceptor bound exciton. For the two Mg acceptor states, we determine binding energies of 164 ± 5 and 195 ± 5 meV, which is in good agreement with recent density functional theory results. This observation confirms and quantifies the general dual nature of acceptor states in GaN based on the presented analysis of the photoluminescence and photoluminescence excitation spectra.