标题： 光致变色效应及点缺陷电荷状态对氮化铝（AlN）光学吸收的影响 显示英文标题

标题： Photochromism and influence of point defect charge states on optical absorption in aluminum nitride (AlN)

摘要： 在本工作中，我们研究了AlN在1.5-5.5 eV范围内的吸收特性，以及由紫外（UV）照射引起的吸收的亚稳态变化（光致变色效应），以及在2-4 eV照射或升高温度作用下初始状态的恢复。 UV照射导致4.7 eV处的吸收系数从110 cm$^{-1}$降低到55 cm$^{-1}$，而在可见光范围内，吸收系数从低于5 cm$^{-1}$增加到约35 cm$^{-1}$。 使用两种线性偏振方向（平行和垂直于光轴）的测量，确定了2.6、2.8、3.4、4.0、4.5和4.8 eV处的几个不同的吸收带。 2.6 eV和3.4 eV处的带表明接近价带的缺陷能级，而峰值位于2.8 eV处的带与导带有关。 光致变色效应允许控制两个相关光谱范围内的光吸收，因为UV吸收的减少和可见光吸收的增加与相同缺陷的电荷状态切换有关。 显示英文摘要

摘要： In this work, we study the absorption properties of AlN in the range of 1.5 - 5.5 eV, as well as the meta-stable change in absorption induced by ultraviolet (UV) irradiation (photochromism), and the restoration of the initial state under the action of irradiation of 2 - 4 eV or elevated temperatures. UV irradiation results in a decrease of the absorption coefficient from 110 cm$^{-1}$ to 55 cm$^{-1}$ at 4.7 eV while in the visible range the absorption coefficient increases from values below 5 cm$^{-1}$ to ~35 cm$^{-1}$. Measurements with two linear polarizations, parallel and perpendicular to the optical axis, provide determination of several different absorption bands at 2.6, 2.8, 3.4, 4.0, 4.5, and 4.8 eV. The bands at 2.6 eV and 3.4 eV identify the defect levels near to the valence band, while the band peaking at 2.8 eV is related to the conduction band. The photochromism allows controlling the absorption of light in two related spectral ranges because the decrease of UV absorption and increase of the visible absorption are related to switching the charge state of the same defects.