Hall Effect Of Amorphous Silicon Fabricated By A Low-pressure Chemical Vapour Deposition Method

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Du, Ning
Physics; Electricity and Magnetism
thesis / dissertation description
Hall Effect measurements on various amorphous materials reported so far have the following common features: (i) the Hall mobility lies between 0.01 to 0.1 cm{dollar}\sp2{dollar}/V.s. at room temperature and increases slightly with the measurement temperature; (ii) the sign of Hall coefficient is anomalous. We have started an extensive research program to study the Hall effect of a-Si thin films fabricated by the LPCVD (low pressure chemical vapour deposition) method and observed, for the first time, normal Hall coefficient in some amorphous LPCVD samples with good network structured. For instance, the Hall mobility of sample CP119 (phosphorus doped) is 0.16cm{dollar}\sp2{dollar}/V.s. and Hall coefficient is negative. The structure of this sample is amorphous as confirmed by x-ray diffraction, Raman spectroscopy, transmission electron microscopy and transport properties. We believe that amorphous material with good short range order should have the normal Hall coefficient. Doping efficiency of {dollar}\mu{dollar}c-Si fabricated by LPCVD is also studied by Hall effect and SIMS measurement. Electrical compensation model works well for {dollar}\mu{dollar}c-Si.