Improving the quality of the evaporated Ge nanodot arrays by laser annealing

To improve the quality of deposited amorphous germanium (a-Ge) on the Si substrate, a re-crystallization method of a-Ge by laser annealing is demonstrated. Laser annealing has two important advantages: high energy density E (700, mJ/cm²) is melting the a-Ge and a lot of laser spot quantity (20 spots) is alteration the a-Ge quality. These two factors were carefully designed to fabricate the high quality crystalline Ge(c-Ge). High laser energy density E and a lot of laser spot quantity would transform the a-Ge nanorod into c-Ge nanodot due to Ge´s high cohesion. In addition, the size and distribution of Ge-nanodot arrays can be defined with the electron beam (E-Beam) lithography. The quality of re-crystallized Ge-nanodot arrays as characterized with Micro-Raman. To characterize the crystallinity, the Raman spectrum is fitted with the Lorentz distribution. The result shows that the narrow FWHM is 3.5278 cm^-1 and peak position at 303.889 cm^-1, which is close to that of single crystal Ge. It implies that the quality of there crystallized Ge-nanodot arrays are almost the same as that of single crystal Ge and the strain is fully relaxed. In summary, the high quality of crystalline germanium (c-Ge) nanodot arrays on Si substrate can be achieved by laser annealing.