Temperature dependent aluminum induced crystallization of amorphous germanium thin films

[Display omitted] •Growth of poly-Ge films on quartz glass via thermal evaporation method.•Annealing induced morphology evolution for preferential crystal growth.•Impact of heat treatment on the microstructural, electrical, and optical properties.•Better crystallinity in conjunction with reduction in localised band tail states confirmed by the red-shift in band gap.•Phase-inversion from amorphous-to-polycrystalline Germanium thin films. In this work, we present the sequential growth of metal–semiconductor bilayer structure on HF-treated textured glass substrates by thermal evaporation method. The process of aluminum-induced crystallization of amorphous germanium thin films was critically observed under heat treatment. Temperature assisted structural modifications triggered the nucleation phenomenon for controlled grain growth which transformed the nature of Ge-thin film from amorphous-to-polycrystalline. Interestingly, the electrical resistivity also decreased by subsequent annealing which promoted the conduction mechanism. Optical measurements indicated a dwindling in band tail states and related structural defects, leading to better crystallinity.