In situ transmission electron microscopy observations of the crystallization of amorphous Ge films

The crystallization of amorphous Ge films has been studied as a function of annealing temperature between 400 and 700°C by in situ transmission electron microscopy (TEM). It is found that crystallization does not occur until the annealing temperature reaches 650°C, which is nearly 250°C higher than the crystallization temperature in previous reports. The high crystallization temperature and average crystal size obtained by in situ TEM are in agreement with those from Raman spectroscopy and X-ray diffraction measurement. The kinetics analysis indicates that homogeneous nucleation is the dominant crystallization mode and the activation energy is up to about 3.1 eV.