Electrostatic powder impact deposition (EPID) of Ge on Si and Cu substrates, microstructure and morphology study

Electrostatic powder impact deposition (EPID) is a novel method to deposit thin films by electrostatic acceleration of powder material between charged plates in vacuum. The EPID method has been used to deposit Ge films on Si and Cu substrates at room temperature. Surface morphology and microstructure as studied by SEM showed a very rough surface. XRD and RBS measurements revealed that the films were mostly nanocrystalline or amorphous Ge oxide. The grain size distribution of the Ge powder was measured before and after deposition. Initial distribution showed a median grain size of 32 µm and distribution width of 80 µm. After the deposition the median grain size had decreased to 16 µm and the width decreased to 55 µm. The grain size of the deposited film was less than 1 µm.