PHASE-CHANGE RECORDING USING A SCANNING NEAR-FIELD OPTICAL MICROSCOPE

The formation and observation, with reflected light, of 60-nm-diam pha se-changed domains in a thin GeSbTe film using a scanning near-field o ptical microscope with a 785 nm wavelength laser diode is demonstrated . The dependence of the domain size on incident laser power was obtain ed, and the size changed from 150 to 60 nm in diameter with incident p ower of 8.4-7.3 mW in the probe. At the threshold power of 7.3 mW, the film temperature rose to around 180 degrees C to partially phase chan ge the local area of the film from amorphous to crystalline. A detecte d reflectivity increase due to phase change in the formed domain was 8 %-2%. The observing (reading) was performed with an incident laser pow er of 0.2 mW, which corresponds to 10(-2)-10(-3) times less than in a magneto-optical recording. The incident laser power shows that the pha se change reading using the reflection scanning near-field optical mic roscope has the potential to read the recorded bit at a speed over 10 MHz. (C) 1996 American Institute of Physics.