Improvements in quantum efficiency of excitonic emissions in ZnO epilayers by the elimination of point defects
Improvements in quantum efficiency of excitonic emissions in ZnO epilayers by the elimination of point defects
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DOI：
10.1063/1.2193162
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发表时间：
2006-05
影响因子：
3.2
通讯作者：
S. Chichibu;T. Onuma;M. Kubota;A. Uedono;T. Sota;A. Tsukazaki;A. Ohtomo;M. Kawasaki
中科院分区：
文献类型：
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作者：
S. Chichibu;T. Onuma;M. Kubota;A. Uedono;T. Sota;A. Tsukazaki;A. Ohtomo;M. Kawasaki
通过消除ZnO外延层中的点缺陷，以及在ScAlMgO 4衬底上采用ZnO高温退火自缓冲层（HITAB）作为外延模板，显著提高了ZnO外延层近带边激子光致发光（NBE）的内量子效率（ηint）.带负电荷的Zn空位（VZn）的浓度大大降低了高温生长，和较慢的生长后冷却（退火）下的最低氧压进一步降低了总浓度的正，负电荷和中性点缺陷，根据抑制非平衡缺陷淬火。降低点缺陷的总浓度和VZn的浓度均能提高室温下的无辐射PL寿命（τnr）。因此，某些点缺陷配合物与VZn（VZn-X复合物）被分配到占主导地位的非辐射复合中心。由于消除了点缺陷，因此，
The internal quantum efficiency (ηint) of the near-band-edge (NBE) excitonic photoluminescence (PL) in ZnO epilayers was significantly improved by eliminating point defects, as well as by the use of ZnO high-temperature-annealed self-buffer layer (HITAB) on a ScAlMgO4 substrate as epitaxial templates. Negatively charged Zn vacancy (VZn) concentration was greatly reduced by high-temperature growth, and slower postgrowth cooling (annealing) under minimum oxygen pressure further reduced the gross concentration of positively and negatively charged and neutral point defects, according to the suppression of nonequilibrium defect quenching. The nonradiative PL lifetime (τnr) at room temperature was increased by decreasing the gross concentration of point defects, as well as by decreasing the concentration of VZn. Accordingly, certain point defect complexes incorporated with VZn (VZn-X complexes) are assigned to the dominant nonradiative recombination centers. As a result of the elimination of point defects, a re...