Yuan Junxiao, Hou Yidong, Chen Feiliang, Li Qian
Microsystem and Terahertz Research Center, China Academy of Engineering Physics, Chengdu, 610299, China.
Department of Physics, Sichuan University, Sichuan, 610065, China.
J Phys Chem A. 2024 Mar 21;128(11):2130-2135. doi: 10.1021/acs.jpca.4c00564. Epub 2024 Mar 8.
The defect-based single-photon emitters (SPEs) in gallium nitride (GaN) have attracted considerable research interest due to their high emission rate, narrow line width, and room-temperature operation. However, the quenching effect greatly restricts the applications of these SPEs, and the origin of the quenching mechanism is still unclear. Here, based on systematic ab initio calculations, we reveal a possible quenching mechanism originating from the transformation between two different structures of the defect-pair NV in wurtzite GaN. Our results indicate that the defect-pair NV possesses two stable detect-structures A and B, where the structure B has a small zero phonon line (ZPL) and long lifetime. The transformation barrier from structures A to B is only 0.097 eV. Thus, structure A can easily transform to structure B under laser illumination due to thermal fluctuations, causing a quenching phenomenon. Our work also predicts that the barrier energy between defect structures A and B could be effectively adjusted through tuning the triaxial compressive strain of the crystal structure. This provides an effective method to suppress the quenching effect of defect-pair NV in GaN, paving the way for practical applications of SPEs.
氮化镓（GaN）中基于缺陷的单光子发射体（SPEs）因其高发射率、窄线宽和室温工作特性而引起了广泛的研究兴趣。然而，猝灭效应极大地限制了这些SPEs的应用，且猝灭机制的起源仍不明确。在此，基于系统的从头算计算，我们揭示了一种可能的猝灭机制，其源于纤锌矿型GaN中缺陷对NV的两种不同结构之间的转变。我们的结果表明，缺陷对NV具有两种稳定的检测结构A和B，其中结构B具有较小的零声子线（ZPL）和较长的寿命。从结构A到B的转变势垒仅为0.097 eV。因此，由于热涨落，结构A在激光照射下很容易转变为结构B，从而导致猝灭现象。我们的工作还预测，通过调整晶体结构的三轴压缩应变，可以有效地调节缺陷结构A和B之间的势垒能量。这为抑制GaN中缺陷对NV的猝灭效应提供了一种有效方法，为SPEs的实际应用铺平了道路。
