P-type Cualo <sub> 2 </ Sub> Polycrystalline Target And Thin Films

With broad application prospects, p-type delafossite CuAlO2 (CAO) can be used as transparent semiconductor devices. However, it is very difficult to fabricated high conductivity and transmittance CuAlO2 thin films. CuAlO2 ceramic targets have been fabricated by solid-state sintering method. And then CuAlO2 thin films have been fabricated on sapphire substrate by pulse laser deposition technology. For improve optical and electrical properties, Cobalt doping in GuAlO2 have been done at the first time.Taken AR-micron Al2O3 and Cu2O powder as raw materials, CuAlO2 ceramic targets have been prepared by solid-state sintering. Structure and performance of CuA102 ceramic targets have been measured by XRD,RT,Raman and SEM. Furthermore, effects of sintering temperature and time on structure, density and conductivity of CuAlO2 ceramic targets have been investigated. The experiment results shown that the optimum sintering temperature and time is 1150℃and 10 hours respectively. Density of p-type CuAlO2 targets is 4.83g/cm3, electrical conductivity at room temperature is 1.3×10-2S.cm-1, and activation energy is 0.265eV.CuAlO2 thin films have been successfully prepared by pulsed laser deposition. And post-annealing has been investigated. Structure and performance of CuAlO2 thin films have been measured by XRD,R-T,XPS and Uv-vis. Furthermore, effects of annealing temperature and time on structure and performance of CuAlO2 thin films have been investigated. X-ray diffraction analysis shows that the thin film is oriented (001) at 1050℃,10min. XPS analysis shows that the valence of Cu is+1, and Al is+3, it's equal to the valence state of elements in CuAlO2. The transmittance of CuAlO2 thin films is about 70% at the range of visible lights. The activation energy of CuAlO2 thin films is 0.393ev by lnσ-1000/T curve.For improve conductivity and transmittance of CuAlO2, it's the first time doping Co to substitute Al. In accordance with the optimum experimental conditions, CuAl1-xCoxO2 ceramic targets and thin films have been successfully prepared. As the doping ratio increases, the content of CuO is increased, too. XRD peak of Co oxide have not been found, it perhaps is that Co content is less or Al substitute by Co partly. CuAl1-xCoxO2 thin films have been prepared by pulsed laser deposition. By post-annealing, high quality CuAl1-xCoxO2 thin films has been obtained. However, the resistance of CuAl1-xCoxO2 thin films is still large. The reason is possibly due to Co have been insert into the grain boundaries, impeding the migration of carriers as the formation of the absorption and scattering centers.