We analyzed the Ge/Si(100) phase composition based on existing literature data and results obtained with high-resolution electron microscopy method. The research confirms formation of solid solutions Ge(Si) in the Ge film and the Si(Ge) in the Si (100) substrate, which are separated by a thin pseudomorphic layer. This conclusion can correctly interpret the phase composition of the heterostructure based on Ge and Si. An array of tips developing on the interface with the tip density of the order 10<^>14 m<^>-2 was visualized. The emission properties of the tips were studied, including electric field strength near their peaks reaching 10<^>9 V/m, which causes cold emission.