Highly accurate measurement of crystallization temperature of hydrogenated amorphous silicon films

研究了一种高精度测量氢化非晶硅(a-Si：H)薄膜微晶化温度的新方法。取得了以下研究成果：1.析氢特性测量系统的改进。为了获得清洁的真空系统，我们用涡轮分子泵取代了油封的旋转泵。通过计算机进行高速的数据处理和分析。微晶温度的最佳测量条件：考察了真空压力、升温速率、样品大小、原子质量数、分析仪灵敏度等测量析氢特性的最佳条件。利用析氢特性、X射线衍射和电学性能研究了a-Si：H薄膜的微晶化过程。发现a-Si：H薄膜的微晶化过程强烈地依赖于晶核生长的激活能和晶核的密度。通过以上结果和讨论，我们认为可以利用析氢特性进行高精度的晶化温度测量。此外，我们还发现，这种方法比传统的基于X射线衍射法的方法更简单，并且只需要一个样品就可以测定微晶化温度。这种方法将有助于根据a-Si：H薄膜的结构来评价其质量，以及高精度地测量微晶化温度。

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.