Raman imaging of Ge under heating

Laser wavelength532 nm
Objective lensx10 (NA=0.30)
The number of spectra2,000(200×10) ※The spectra in the figure below are an example.
Measurement time11 min.

The figure above shows an example of Raman image of Ge crystallized by metal induced crystallization (MIC) method, observed at 400 ℃. The obtained image shows that the crystalline Ge on the SiO2/Si substrate is formed around Au. From the Raman spectra obtained, crystalline Ge (red), amorphous Ge (blue), and the intermediate form (green) can clearly be distinguished from each other.

Observation of crystalline Ge growing around Au nuclei

Raman spectroscopy can be applied to in-situ observation at high temperature. The figure below, where profiled by the peak intensity of crystalline Ge, shows crystalline Ge growing from the Au catalyst to the region of amorphous Ge. In this measurement, the sample temperature increased by 20 ℃/minute. As increasing the temperature, the area of crystallized Ge spreads to the right in the figure.

cf. Metal induced crystallization (MIC) method

The MIC method is a technique to fabricate thin films of group-IV semiconductor at a low temperature. In this technique, crystallization is induced in the in-plane direction around metal nuclei deposited on the thin film of amorphous semiconductor. Using this method, crystalline semiconductor thin films can be fabricated even on the glass substrate where the high temperature process is not available. This method can be a potential technique to achieve high-performance sheet computers.

※This sample was provided by Dr. Isao Tsunoda , National institute of technology, Kumamoto college.