Ga:ZnO based transparent conducting oxides and devices

摘要

We report on the synthesis and processing, and structure - property correlations in gallium doped ZnO firms grown on (0001) sapphire and glass substrates by pulsed laser deposition. Films with varying microstructure were grown on amorphous glass by changing the pulsed laser deposition parameters, namely temperature and oxygen partial pressure. The results corresponding to these films were compared with those from epitaxial single crystal films grown on (0001) sapphire. It is shown that resistivities and transmittance comparable to epitaxial Zn_(0.95)Ga_(0.05)O films (ρ=1.4 × 10~(-4)Ω-cm, %T > 80) can be achieved in the nanocrystalline films (ρ=1.8 × l0~(-4)Ω-cm, %T > 80) deposited on glass by carefully controlling the deposition parameters. We have investigated and modeled the conduction mechanisms (carrier generation and carrier transport) in the novel Ga:ZnO films through detailed structural characterization, chemical analysis, and electrical and optical property measurements. The device applications based on these highly conducting and transparent films as electrodes will also be discussed. Our preliminary results have demonstrated that power conversion efficiencies comparable to indium tin oxide (ITO) based organic photovoltaic devices can be achieved using ZnGaO films as the anode.