Crystallization of Amorphous Silicon Thin Films by Microwave Heating. Issue 1666 (3rd November 2014) - Nakamura, Tomohiko
ABSTRACT: We report crystallization of amorphous silicon (a-Si) thin films and improvement of thin film transistors (TFTs) characteristics using 2.45 GHz microwave heating assisted with carbon powders. Undoped 50-nm-thick a-Si films were formed on quartz substrates and heated by microwave irradiation for 2, 3, and 4 min. Raman scattering spectra revealed that the crystalline volume ratio increased to 0.42 for the 4-min heated sample. The dark and photo electrical conductivities measured by Air mass 1.5 at 100 mW/cm 2 were 2.6x10 -6 and 5.2x10 -6 S/cm in the case of 4-min microwave heating followed by 1.3x10 6 -Pa-H2 O vapor heat treatment at 260°C for 3 h. N channel polycrystalline silicon TFTs characteristics were improved by the combination of microwave heating with high-pressure H2 O vapor heat treatment. The threshold voltage decreased from 5.3 to 4.2 V and the effective carrier mobility increased from 18 to 25 cm 2 /Vs.