Influence of Heat Treatment Temperature and of Sb2O3 addition on Photoluminescence Properties of ZnO Ceramics Prepared by Sol-Gel Technique Preparation

To explore thin transparent electroluminescence and electric conductive films by sol-gel technique, Sb2O3 doped n-type ZnO ceramics powders were prepared by sol-gel technique and photoluminescence properties were measured. Then, the influences of composition and heat treatment temperature on photoluminescence properties were investigated in detail. With respect to the dopant concentration, about 1mol% addition of Sb2O3 was effective to increase photoluminescence intensity. With respect to heat treatment temperature, 800℃ was appropriate, and rather higher heat treatment temperature resulted in the formation of Zn7Sb2O12 and decrease the intensity. The excited ultraviolet wavelength of 200nm was proper to intense photoluminescence.

• Zno Ceramics
• Sb2O3 Doping
• Photoluminescence
• Heat Treatment Temperature
• Sol-Gel

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)

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