不同退火温度下晶化硅薄膜的电学输运性质

采用等离子体化学气相沉积技术制备氢化非晶硅薄膜，经过不同温度下的热退火处理，使薄膜由非晶结构向晶化结构转变，得到含有纳米晶粒的晶化硅薄膜.在晶化过程中，采用Raman技术对样品的结构进行表征.通过变温电导率的测试，对薄膜的电学输运性质进行了分析.研究结果表明：退火温度为700 ℃时,样品中开始有纳米晶形成，随着退火温度的增加，样品的晶化比增大，在1000 ℃时，薄膜的晶化比达到90%以上.在700 ℃退火时，薄膜中晶化成分较低，载流子的传输特性主要受到与硅悬挂键有关的缺陷态影响，表现为带尾定域态的跳跃电导 关键词： 氢化非晶硅 退火 纳米硅 电输运

Properties of electric transport in crystallized silicon films under different annealing temperatures

Hydrogenated amorphous Si thin films were prepared by plasma-enhanced chemical vapor deposition. As-deposited samples were annealed at different temperatures to obtain nano-crystalline Si. During the transition process from amorphous to nano-crystalline structure, Raman scattering spectroscopy was used to characterize the changes of microstructures. The temperature-dependent conductivity was measured in order to understand the electric transport processes in the films. It was found that the crystallization occurs at around 700 ℃. The crystal volume fraction (X_c) increases with the increase of annealing temperature, and in the case of the Si film annealed at 1000 ℃, the X_c is beyond 90% . The carrier transport characteristics in the films annealed at the different temperatures are different from the as-deposited film. For the sample annealed at 700 ℃, the carrier transport is strongly influenced by the defect states resulting from the effusion of hydrogen, and it is controlled by the hopping conduction of the localized states in the difference measurement temperature regions causing the dual activation energies. For the highly crystallized Si film annealed at 1000 ℃, the transport process is strongly influenced by the transport of the extended states in the crystalline silicon, while in the high temperature region, the quantum tunneling process plays an important role in the carrier transport property.