采用近空间升华法在玻璃衬底上制备PbI2厚膜,研究了工艺参数对样品晶体结构、形貌和光致发光性质的影响。实验显示,沉积速率随着源温度的升高和沉积气压的下降而急剧增大。XRD谱表明PbI2膜为沿[001]晶向择优取向的六方多晶体,晶粒尺寸随沉积速率的增大而逐渐减小。同时,沉积速率增大还导致膜压应力变大,晶格常数减小,使（001）晶面衍射峰向大角度方向移动。SEM照片显示样品为（001）晶面堆积而成的片状晶粒结构,晶粒c轴与衬底平行。随着沉积速率的增大,晶粒有序性和膜致密度下降,同时（001）晶面上由于六方中心亚晶粒的出现而导致表面粗糙度大幅增大。样品的PL发光谱显示了本征发射特征,发光锋随沉积速率的增大向长波方向移动,同时峰位展宽,强度减弱。
Polycrystalline PbI2 thick films were grown on glass substrates using close-spaced sublimation（CSS） technique,and its structural,morphological and photoluminescent（PL） properties as a function of deposition condition were investigated.It was found that the deposition rate increases rapidly with increasing sublimation source temperature and decreasing deposition pressure.The crystal structure and surface morphology of samples as function of deposition rate was characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results reavealed PbI2 thick films have a layered hexagonal structure,formed by the stacking of（001） plane,with a prefferred orientation,and the grain size decreases with increasing deposition rate.Meanwhile,the（001） diffraction peaks（2θ） was shifted towards large-angle as a result of decreasing lattice constant attributes to increasing films compressive stress.The SEM images of samples also show that the（001） orientation（c-axis） of layered grains is parallel to the substrate,and its ordering degree as well as film density reduces with the increases of deposition rate.Furthermore,high deposition rate also presents ＂hexagonal center＂ subgrain,grown perpendicularly on the layered grains,lead to a dramatically improve in surface roughness.Finally,the samples PL spectra only exhibit intrinsic luminescence,and the PL peak shifted to longer wavelengths with braoden peak width and lower intensity,owing to increasing deposition rate.
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