Influence of Heat Treatment Temperature and of Sb2O3 addition on Photoluminescence Properties of ZnO Ceramics Prepared by Sol-Gel Technique Preparation ()
1. Introduction
ZnO is aⅡ-Ⅵ type semiconductor with direct transition of 3.37 eV. Further, the exciton binding energy is 60 meV at room temperature, while which of GaN currently used for blue light emitting diode (LED) is 25 meV. Moreover, GaN is a point contact LED, which means that it cannot be used as plane display, although ZnO ceramics can be considered to be used as plane LED. That is significant advance in display application. Recently, the successful preparation of ZnO diode which has 10 times larger emission efficiency than GaN LED was reported [1]. Thus, ZnO is a promising material for the future display device.
For the practical use of ZnO ceramics, it should have electroluminescence property. Al or Ga was successfully doped in ZnO and make it electrically conductive [2-4]. Similarly, the addition of Sb2O3 is expected n-doped ZnO making electric conductive. However, no report has been concerned with the influence of Sb2O3 doping into ZnO ceramics to the author’s knowledge.
To develop electroluminescence materials, photoluminescence property is important since the relaxation process is quite similar. The difference between those properties is only the difference in electron excitation process. The oxygen defects can be considered to cause emission process [4,5]. Thus, emission process and electrically conducting process are pointed out to be relating oxygen vacancies [6,7]
The sol-gel preparation technique is quite useful and easy technique to prepare thin oxide films because of the technique using solution state, and it is applicable to prepare ZnO ceramics on transparent glass substrate [8-10]. The advantages of the sol-gel technique for film preparation is the possible coating on the complicate shapes of the surfaces, the preparation under the ambient atmosphere at room temperature and the high homogeneity of the resultant products.
Therefore, this paper reports sol-gel preparation of Sb2O3 doped ZnO polycrystalline ceramics and these photoluminescence properties.
2. Experimental Procedure
Figure 1 indicates the flowchart of the sample preparation. The raw chemicals were commercially available, and analytical grade Zn(CH3COO)2・2H2O, SbCl3, NH2CH2CH2OH(MEA) and CH3OC2H4OH(MEH)