Highly accurate measurement of crystallization temperature of hydrogenated amorphous silicon films

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A new method for measuring the microcrystallization temperature of hydrogenated amorphous silicon (a-Si : H) films with high accuracy was studied by using hydrogen evolution characteristics. The following results were obtained.1. Improvement in the measuring system of hydrogen evolution characteristics.To obtain a clean vacuum system, we replaced an oil-sealed rotary pump with a turbo-moleculer pump. High-speed data processing and analysis were carried out through the computer.2. Optimum conditions for measuring the microcrystallization temperature.Optimum conditions for measuring hydrogen evolution characteristics such as vacuum pressure, temperature raising-rate, sample size, atomic mass number and sensitivity of analyzer, were examined.3. Structural changes of the film with its microcrystallization.Microcrystallization process in a-Si : H films has been studied by means of hydrogen evolution characteristics, X-ray diffraction and electrical properties of the films. Microcrystallization process of a-Si : H films was found to depend strongly on both the activation energy of the growth of crystalline nuclei and the density of crystalline neclei.From the above results and discussion, we concluded that the highly accurate measurement of crystallization temperature would be performed by means of the hydrogen evolution characteristics. Moreover, we found that this method is simpler than the conventional method based on X-ray diffraction, and requires only one sample for the determination of microcristallization temperature. This method will be useful for the evaluation of the quality of an a-Si : H film on the basis of the film structures, as well as the high-accurate measurement of microcrystallization temperature.