| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
In this research, crystal growth technique of atomic layer epitaxy (ALE) was used to obtain n- and p-type ZnO thin films.
At first, ZnO thin films were grown on sapphire substrates using diethylzinc (DEZ) and water (H_2O) as precursors. By optimizing the growth conditions, ALE growth conditions of ZnO thin films were clarified. In addition, it was observed that the GaN templates were effective to improve the crystal quality of ZnO thin films.
By using triethylgallium (TEG) as n-type dopant, it was observed that the electron concentration was increased with the increase of the amount of supplied TEG.
On the other hand, monomethylhydrazine (MMHy) was used as p-type dopant. Raman spectra revealed nitrogen (N)-related vibrational modes at 275, 510, 582 and 643 cm^<-1> in addition to the host phonons of ZnO. The intensity of these additional modes was increased with increasing the amount of MMHy. However, as-grown MMHy-doped ZnO films showed n-type conductivity. In order to activate N atoms as acceptors, thermal annealing in oxygen ambient was performed. By capacitance-voltage (C'V) measurements, MMHy-doped ZnO layer annealed at 800 ℃ showed p-type conductivity with the hole concentration of 2×10^<15> cm^<-3>. In addition, the neutral acceptor-bound exciton (A^0X) emission and donor-acceptor pair (DAP) emission were observed in N-doped ZnO layer annealed at 800 ℃ by low temperature photoluminescence (PL) measurements.
These results suggest that n- and p-type ZnO thin films were obtained and the conductivity controlled ZnO thin films were successfully grown by ALE.
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