Excitonic Molecule Bound to the Isoelectronic Nitrogen Trap in GaP
Excitonic Molecule Bound to the Isoelectronic Nitrogen Trap in GaP
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DOI：
10.1103/physrev.188.1228
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发表时间：
1969-12
期刊：
影响因子：
--
通讯作者：
J. Merz;R. A. Faulkner;P. J. Dean
中科院分区：
文献类型：
--
作者：
J. Merz;R. A. Faulkner;P. J. Dean
两组尖锐的发射线，与GaP中的等电子氮陷阱的光致发光光谱相关联，被明确地确定为第二激子结合到这个中心的能量为10毫电子伏的重组。这是第一次观察到激子分子与缺陷结合。复合体中的两个电子和两个空穴联合收割机形成两个反对称态，其角动量分别为${J}_{t}=0$和${J}_{t}=2$。${J} t}=2$态被立方晶场分裂0.16 meV，${J} t}=0$态位于该双重态重心上方0.17 meV。从这些国家的$A$和$B$状态的一个单一的激子绑定到氮的过渡。该模型预测的复杂塞曼分裂与实验结果基本一致。激子分子在低温下是稳定的，在1.5K时，激子分子发射线随抽运功率的增加而增加，与单个激子强度的平方成正比。然而，非辐射俄歇复合使氮的总辐射强度比4.2K时的强度低3倍。第二激子在氮陷阱处的结合能几乎等于单个激子的结合能。这一显著的事实可能只有在等电子陷阱中才有可能。
Two sets of sharp emission lines, associated with the photoluminescence spectrum of the isoelectronic nitrogen trap in GaP, are unambiguously identified as the recombination of a second exciton bound to this center with an energy of 10 meV. This is the first observation of an excitonic molecule bound at a defect. The two electrons and two holes within this complex combine to form two antisymmetric states of angular momentum ${J}_{t}=0$ and ${J}_{t}=2$. The ${J}_{t}=2$ state is split 0.16 meV by the cubic crystal field, and the ${J}_{t}=0$ state lies 0.17 meV above the center of gravity of this doublet. Transitions from these states to the $A$ and $B$ states of a single exciton bound to nitrogen are seen. The complex Zeeman splittings predicted by this model agree in detail with experiment. The excitonic molecule is stable at low temperature; at 1.5\ifmmode^\circ\else\textdegree\fi{}K, the excitonic molecule emission lines increase as the square of the single exciton intensity with increase in pumping power. However, nonradiative Auger recombination reduces the over-all nitrogen emission by a factor of 3 below the intensity at 4.2\ifmmode^\circ\else\textdegree\fi{}K. The binding energy of the second exciton at the nitrogen trap is nearly equal to that of the single exciton. This remarkable fact may be possible only for an isoelectronic trap.