Formation and charging effect of Si nanocrystals in a-SiNx/a-Si/a-SiNx structures

• Published in: Journal of applied physics 2004-01, Vol.95 (2), p.640-645
• Main Authors: Dai, Min, Chen, Kai, Huang, Xinfan, Wu, Liangcai, Zhang, Lin, Qiao, Feng, Li, Wei, Chen, Kunji
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1633649

The sandwiched structures with a layer of amorphous silicon (a-Si) between two a-SiNx layers have been fabricated by plasma enhanced chemical vapor deposition technique. Si nanocrystal (nc-Si) layer was formed by crystallization of the a-Si layer according to the constrained crystallization principle after thermal annealing at 1100 °C for 30 min. Transmission electron microscopy (TEM) and Raman scattering spectra showed that nc-Si grains were formed in the as-deposited a-Si layer after the annealing with a mean size about the same as the thickness of the as-deposited a-Si layer, and the density of the order of 1011–1012 cm−2. Charge trapping and storage in nc-Si were exhibited in capacitance–voltage (C–V) measurements at room temperature through the hysteresis and shift of the flat-band voltage (ΔVFB) of the nc-Si samples after a dc voltage was imposed. The density of nc-Si grains estimated from the ΔVFB was consistent with the results of TEM observation. The origin of the hysteresis phenomena and mechanism of the charge storage were discussed in detail.