超声喷雾法制备掺Zn和未掺Zn α-Fe2O3薄膜的研究

Studies on the preparation of the undoped and Zn-doped α-Fe_2O_3 thin films by ultrasonic spray pyrolysis

使用自制的超声雾化热裂解设备(UPS)成功地制备了掺Zn和未掺Zn的α-Fe2O3薄膜,并对其光电特性进行了较为系统的研究。XRD结果证实了所获得的薄膜为α-Fe2O3,AFM测试结果表明:薄膜致密,晶粒成沟壑状地生长,粒径在0.1μm到0.2μm之间。紫外-可见光谱实验发现Zn掺杂的α-Fe2O3薄膜吸收发生了"红移",带隙发生变化。XRD分析也证实Zn掺杂对Fe2O3的晶体结构有影响。Mott-Schottky测试的结果获得了UPS制备的n型α-Fe2O3薄膜的导带、价带电位,而Zn掺杂α-Fe2O3薄膜的导电类型由n-型转变为p-型,且它的价带、价带电位能够更适合氢和氧的析出。这说明了自制的UPS设备可以用于太阳光水解制氢半导体薄膜材料的制备。

The Zn-doped and undoped α-Fe2O3 thin films were successfully prepared by self-made equipment of ultrasonic spray pyrolysis on glass substrates coated by SnO2 （ FTO）. The thin films were uniform ,adhesive strongly to FTO without pinholes ,and the results of XRD analysis showed that they were both α-Fe2O3 with the average particle size of up-to 0.2 μm proved by AFM. There was an observation of the ＂red shift＂ for absorption of Zn-doped Fe2O3 thin films from UV-vis spectroscopy ,which was an example to modify the bandgap by doping the metal elements such as Zn. The Zn-doped Fe2O3 films were p type, and the band gap was found 2.1 eV which was 100mV bigger than that of the undoped ones with n-type. The flatband potential of the undoped ones was-0. 83V vs SCE at pH = 14, which was more negative, compared with literatures, and the apparent donor density of 3.16 × 10^18 cm^-3 was found from the Mott-Schottky plots at the AC frequency of 1000 Hz. While the flatband potential of the Zn-doped ones was 1.06V vs SCE at pH = 14 and the apparent acceptor density of 1.03 × 10^19cm^-3. The more negative potential of n-Fe2O3 thin films were more suitable for hydrogen generation under visible light. Further experiments for other photoelectric properties like IPCE, I-V curves and water splitting are under way.