Hot-wire chemical vapor growth and characterization of crystalline GeTe films

Films of germanium telluride (GeTe) were grown by chemical vapor deposition (CVD) using pulsed liquid injection/flash evaporation principle to introduce the metalorganic precursor vapors. Simple thermal CVD with no additional process activation and CVD employing hot-wire remote catalytic activation of the precursor decomposition process were investigated and compared. Ge(NMe2)4 and Te(iPr)2 precursors in the form of diluted solutions in toluene were used as source materials for the depositions. Film composition was controlled changing the ratio of injected precursors, while the thickness was directly related to the number of injection pulses. Growth of GeTe films with a clearly better quality was demonstrated via the hot-wire-activated CVD process when compared to the standard thermal CVD. The influence of substrate temperature and deposition pressure on film crystallinity and morphology was studied. Reversible optical phase switching was demonstrated in 40-50 nm thick GeTe films on Si/SiO2 substrates.