CsPbBr_(3)晶体生长及变温霍尔效应研究

The growth and variable temperature Hall effect study of CsPbBr_(3)crystal

以定向凝固法提纯的CsPbBr_(3)多晶为原料,采用垂直布里奇曼法生长出尺寸为∅30 mm×70 mm的CsPbBr_(3)单晶。采用ICP-OES对提纯后的多晶测试表明,提纯后的CsPbBr_(3)多晶中杂质含量减少了28.7%。经XRD和EDS对切割得到的晶片分析发现,晶片的晶面方向属{210}晶面族,晶体中Cs、Pb、Br_(3)种元素分布均匀,原子百分含量符合化学计量比。采用傅里叶红外光谱仪和紫外-可见分光光度计对晶体的透过率测试显示,生长晶体在500~4000 cm^(-1)波数范围内的红外透过率超过75%,紫外短波截止边为552 nm,拟合计算出对应的禁带宽度为2.246 eV。选取7个不同温度点对CsPbBr_(3)单晶进行变温霍尔效应测试发现,生长晶体为P型导电,在250~300 K和300~350 K之间晶体中主要的载流子散射机制分别为声学波散射和电离杂质散射,在150~250 K温度范围内,更符合多种散射机构共同作用的散射机制。进一步拟合载流子浓度p与1/T的关系,计算获得晶体中杂质电离能ΔE_(A)=0.3042 eV。

In this article,directional solidification method was used to purify the CsPbBr_(3)polycrystalline material,and a CsPbBr_(3)single crystal with size of 30 mm×70 mm was successfully grown by vertical Bridgman method.The test results of the purified polycrystalline using ICP-OES showed that the impurity content in the purified polycrystalline CsPbBr_(3)decreased by 28.7%.Analysis of the wafer obtained after cutting using XRD and EDS revealed that the crystal plane direction of the wafer belonged to the{210}crystal plane group,and the Cs,Pb,and Br elements were uniformly distributed in the crystal,with atomic percentages that met the stoichiometric ratio.FTIR and UV-visible spectrophotometers were used to measure the transmittance of the crystal.The results showed that the infrared transmittance of the grown crystal exceeded 75%in the range of 500/cm to 4000/cm.The UV short-wave cutoff edge was 552 nm,corresponding to bandgap energy of 2.246 eV.Seven different temperature points were selected to test variable temperature Hall effect of the CsPbBr_(3)single crystal.The results showed that the grown crystal was a P-type conductor.The main scattering mechanisms of charge carriers in the temperature range of 250 K to 300 K and 300 K to 350 K were acoustic wave scattering and ionized impurity scattering,respectively.In the temperature range of 150 K to 250 K,the scattering mechanism was more consistent with a combination of multiple scattering mechanisms.By further fitting the relationship between the carrier concentration p and 1/T,the ionized energy of impurities in the crystal was calculated to beΔE_(A)=0.3042 eV.