Detection of carrier information in heterojunctions of nanocrystalline/crystalline Si

Hall effect measurements on heterojunctions of nanocrystalline Si:H (nc-Si:H) film with crystalline Si wafer fabricated by plasma enhanced chemical vapor deposition technique were made as a function of temperature (20–300 K) and magnetic field (0–15 T). Magnetic field-dependent resistivity and Hall data were interpreted with the quantitative mobility spectrum analysis (QMSA) method, which successfully separated the two-dimensional electron gases (2DEGs) at the nc-Si:H/c-Si interface from 3D carriers appearing in the films and substrates. Mobilities and densities of 2DEGs for the specimens were measured. Detail analyses about influences of interface and epitaxial layer quality including doping, film thickness and mean size of nanocrystals on the mobilities and densities of 2DEGs at interfaces were carried out. The important role of the amorphous buffer layer within the junction was identified. Origin of high mobility observed in the prepared films was revealed. Forward and reverse current mechanisms as well as the dependence of breakdown voltages on temperature in the operated nc-Si:H/c-Si heterostructure were elucidated.