Quantum plane Confinement effect of Exciton as an example of Boson Confinement

报道了CuCL外延薄膜中量子化激子的研究。这里考虑的薄膜厚度(L)远小于光子波长(λ)是介质(-160 nm)，但大于激子玻尔半径a_B(-0.7 nm)。在Z_3激子区的透射谱和吸收谱中观察到了许多结构。当L&lt；30 nm时，这些结构与量子数为n的受限激子能级有很好的对应。对于奇数n，n阶量子化激子的振子强度与L/n^2成正比，对于偶数n，其振子强度与零成正比。当长波近似成立时，用受限激子系统中的宇称选择规则解释了光谱中不存在偶数n态的原因。测量的光谱与附加边界条件自由响应理论进行了比较。理论计算的偏振干涉条纹与实验结果符合得很好，无论是厚膜还是薄膜。通过对吸收线形的分析，讨论了量子化激子的非辐射衰减与量子数n和L膜厚的关系。

A study of quantized excitons in CuCl epitaxial thin films is reported. Film thickness (L) that are much smaller than the photon wavelength (lambda) is the medium (-160nm), but larger than the exciton Bohr radius a_B (-0.7nm), are considered here. Many structures have been observed in transmission and absorption spectra over the Z_3 exciton region. When L<30nm, these structures correspond well to the confined exciton levels with odd quantum number n. The oscillator strength for the nth quantized exciton is found to be proportional to L/n^2 for odd n and zero for even n. The absence of the states with even n in the optical spectra is interpreted in terms of the parity selection rule in the confined exciton system when the long-wavelength approximation holds. The measured optical spectra are compared with the additional-boundary condition-free response theory. Polariton-interference fringes given by the theory demonstrate a good agreement with the experimental results both for thick and thin films. By analyzing the absorption line shape, the dependence of nonradiative damping of the quantized exciton on quantum number n and film thickness L is discussed.