Atomic layer deposition of tin oxide thin films from bis[bis(trimethylsilyl)amino]tin(II) with ozone and water

Tin oxide thin films were grown by atomic layer deposition (ALD) from bis[bis(trimethylsilyl)amino]tin(II) with ozone and water. The ALD growth rate of tin oxide films was examined with respect to substrate temperature, precursor doses, and number of ALD cycles. With ozone two ALD windows were observed, between 80 and 100 °C and between 125 and 200 °C. The films grown on soda lime glass and silicon substrates were uniform across the substrates. With the water process the growth rate at 100–250 °C was 0.05–0.18 Å/cycle, and with the ozone process, the growth rate at 80–200 °C was 0.05–0.11 Å/cycle. The films were further studied for composition and morphology. The films deposited with water showed crystallinity with the tetragonal SnO phase, and annealing in air increased the conductivity of the films while the SnO₂ phase appeared. All the films deposited with ozone contained silicon as an impurity and were amorphous and nonconductive both as-deposited and after annealing. The films were further deposited in TiO₂ nanotubes aiming to create a pn-junction which was studied by I-V measurements. The TiO₂ nanostructure functioned also as a test structure for conformality of the processes.