Final Report Page: 4 of 10
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DE-EE0000577 Final Report
2A13+ + 60H -, A12Q34 + 3H20 (R3)
In addition to Al, Ga has also been attempted as a n-type dopant in ZnO to achieve low
resistivity. The precursor for Ga is Ga(NO3)3. The doping mechanism for Ga-doped ZnO is
similar to that of Al-doped ZnO, by co-precipitation as revealed by cyclic voltammetry.
In both Al-doped and Ga-doped cases, detailed studies of the sheet resistance of the
doped ZnO films as a function of Al(NO3)3 or Ga(NO3)3 concentration in the deposition solution
are carried out, in an attempt to minimize the resistivity of the doped ZnO films.
2) Task 3: Post-Deposition Annealing
This task for Al-doped and Ga-doped ZnO has been successfully completed. The
optimized post-deposition annealing conditions for Al-doped ZnO are found to be 200 C for 3
hours in air. The minimum sheet resistance for Al-doped ZnO achieved is 13.8 Q/w, which
occurs with an A3/Zn2+ ratio of 0.001 in the deposition solution. The corresponding resistivity
for the Al-doped ZnO is 8x10-4 Q-cm.
For Ga-doped ZnO, the optimum post-deposition annealing conditions are found to be
300 C for 2 hours in vacuum 4Torr). The minimum sheet resistance for Ga -doped ZnO
achieved is 7 Q/w and the corresponding resistivity of the Ga-doped ZnO is 3.8x10-4 Q-cm. This
meets the resistivity requirement for TCOs in solar cells. The sample is deposited in a solution
with a Ga3+/Zn2+ ratio of 0.0064.
3) Task 4: Investigation of Film Properties
Energy dispersion spectroscopy is carried out to determine the Al content in Al-doped
ZnO as a function of A3/Zn2+ ratio in the deposition solution. The Al/Zn ratio in the film
corresponding to the minimum sheet resistance of 13.8 Q/w is 0.02. Optical characterization
reveals high transmissivity (>80%) for Al-doped ZnO, which meets the transmissivity
requirement for TCOs.
For Ga-doped ZnO, energy dispersion spectroscopy reveals the Ga/Zn ratio in the film
corresponding to the minimum sheet resistance of 7 Q/w is 0.23. Optical characterization reveals
high transmissivity (80%) for Ga-doped ZnO. X-ray diffraction confirms that Ga-doped ZnO
deposited under the conditions described above is actually ZnO.
3.2 F-Doped ZnO
1) Task 2: Electrodeposition of F-Doped ZnO
This task has been completed. The deposition solution contains 0.5 M Zn(NO3)2 as the Zn
precursor and 0.6 M NaF as the F precursor, which meet the solubility requirement. The
complaxing agent used is EDTA (CiOH16N208) at 0.5 M. The solution pH is adjusted to 7 by
adding NaOH. It is found that 0.5-M EDTA allows the solution pH to be increased to ~10
without Zn(OH)2 precipitation. The solution temperature is 80 C. Cyclic voltammetry reveals
Total: 10 pages
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Tao, Dr. Meng. Final Report, report, December 22, 2010; United States. (digital.library.unt.edu/ark:/67531/metadc833903/m1/4/: accessed January 21, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.