| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 103 === Cuprous oxide is a direct band-gap semiconductor, energy gap size is 2.1eV
with a high absorption coefficient in the visible region and the obtained cuprous oxide sources easily, copper abundant metal in the earth, this material with low-cost, simple, non-toxic, etc.
In this study, we used chemical bath deposition (Chemical Bath Deposition, CBD) to grow Cu2O in copper substrate, and Ni elements by doping with different concentrations and annealing different temperature.
The Cu2O:Ni films were prepared using copper sulfate (CuSO4)
solution with the addition of Nickel Sulfate (NiSO4) as Ni2+ source. The
molar ratio of NiSO4 to CuSO4 ([NiSO4]/[CuSO4]) was varied from 0 to
0.2.
According to low temperature(15K) PL measurement showed that spectrum include two peaks at 720nm (1.72eV) and 647nm (1.91eV) respectively. The 1.72eV peak is bound exciton composed by oxygen vacancies (VO). The other peak 1.91eV is intrinsic property of the crystal perturbed by the presence of impurity centres or stoichiometry defects. Oxygen vacancies was the cause of n-type film.The PL spectrum results show a peak 906nm (1.37eV) when the annealing temperature is above 500˚C with N2 and O2, and the Cu2O:Ni film will change to p-type by Hot-probe measurement results. When annealing temperature reaches 550˚C ,the 1.91eV peak will vanished, intensity of 1.72eV peak will decreased also, the peak at 1.37eV will be the highest one. This phenomenon can be conjectured that Ni atoms in crystal were steamed and becoming copper vacancies (VCu).
CV measurement results found that after annealing, so Cu2O: Ni carrier concentration decreases, this result can be judged with increasing temperature, film conductive patterns gradually move to P-type.
In Hot-probe system, it found annealing temperature at 500 ℃ and treatment with nitrogen and oxygen, the conductive concentration have been successfully converted from n-type to p-type.
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