Temperature dependence of the free-exciton transition energy in zinc oxide by photoluminescence excitation spectroscopy
Temperature dependence of the free-exciton transition energy in zinc oxide by photoluminescence excitation spectroscopy
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DOI：
10.1063/1.1586977
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发表时间：
2003-07-15
影响因子：
3.2
通讯作者：
Giles, NC
中科院分区：
文献类型：
--
作者：
Wang, LJ;Giles, NC
利用光致发光（PL）和光致发光激发（PLE）光谱跟踪了籽晶化学气相输运法生长的未掺杂ZnO晶体中A激子能量（E-XA）随温度的变化。当T>150 K时，由于A激子复合和它的光学声子（LO）复制叠加，边发射变宽。我们使用PLE来确定E-XA的温度依赖性，通过监测生长的ZnO晶体中常见的宽绿色发射，从而建立了E-XA和PL发射峰能量之间的能量差。在室温下在3.26 eV处的PL发射被示出为偏移约50 meV，以比实际E-XA跃迁更低的能量。的E-XA和PL峰之间的能量差的温度依赖性进行了比较与E-XA-LO复合的线型函数的基础上的预测。在300 K时，PL主要由E-XA-LO复合组成。此外，E-XA跃迁能量的温度依赖性可以用标准表达式来描述，德拜和爱因斯坦温度分别为700+/-30和240+/-5K。ZnO的E-XA-T曲线的斜率在室温附近接近恒定值dE（XA）/dT=-0.35meV/K。(C)2003年，美国物理学会。
Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies are used to track the temperature dependence of the A exciton energy (E-XA) in undoped bulk ZnO crystals grown by the seeded-chemical-vapor-transport method. For T>150 K, the edge emission becomes broad as the A exciton recombination and its longitudinal-optical (LO) phonon replica become superimposed. We use PLE to determine the temperature dependence of E-XA by monitoring the broad green emission commonly observed in as-grown ZnO crystals, and thus have established the energy difference between the E-XA and PL emission peak energies. The PL emission at 3.26 eV at room temperature is shown to be offset by about 50 meV to lower energy than the actual E-XA transition. The temperature dependence of the energy difference between the E-XA and PL peaks is compared with predictions based on the lineshape function for the E-XA-LO recombination. At 300 K, the PL is predominantly composed of E-XA-LO recombination. Further, the temperature dependence of the E-XA transition energy can be described using standard expressions and the Debye and Einstein temperatures are found to be 700+/-30 and 240+/-5 K, respectively. The slope of the E-XA versus T curve for ZnO approaches a constant value of dE(XA)/dT=-0.35 meV/K near room temperature. (C) 2003 American Institute of Physics.