Investigation of HfO 2 doping on GeTe for phase change memory

Abstract

The phase change characteristics of HfO 2 doping on GeTe thin films were investigated by X-ray photoelectron spectroscopy, X-ray diffraction patterns, scanning electron microscope, atom force microscopy, and in situ resistance-temperature measurements. It is shown that the crystallization of amorphous GeTe film could be suppressed by the incorporation of HfO 2, which had a favorable effect on the archival life stability. The activation energy for crystallization increased from 2.36 to 4.69 eV, and the temperature for 10 years data retention increased from 108 to 187 °C with the increasing concentration of HfO 2 form 0 to 12 mol%. Meanwhile, the grain size and surface roughness decreased. Phase change memory based on GeTe–HfO 2 film was fabricated and characterized. A reversible phase change could be trigged by the pulse with at least 100 ns width which was shorter than that of Ge 2Sb 2Te 5 (500 ns). The resistance ratio between amorphous and crystalline states achieved 500 times. The minimum energy necessary for RESET operation of GeTe–HfO 2 based test cell was much smaller than that of Ge 2Sb 2Te 5-based one.