Research On Preparation Of ITO Thin Films And Properties Of ITO/p-Si Contact

Transparent conductive films with good conductivity and high transmittance at the same time are widely used in solar cells, light-emitting diodes, flat-panel displays semiconductor devices. Among these films, indium tin oxide(ITO) film is one of the most widely studied and used transparent conductive films.In this thesis ITO transparent conductive films were deposited on glass and p-type silicon substrates by RF magnetron sputtering. XRD, SEM, Four-probe, Hall effect method and spectrometer were used to show the crystal structure, surface morphology, the electrical and optical performances of the samples. And the contact properties between ITO thin films and p-type silicon were characteried by a keithley 2400 and TLM test system.With an amorphous crystal structure the photoelectric performances of ITO thin films deposited at room temperature were found to be poor. And the photoelectric properties as well as the crystallization properties of ITO thin films deposited at 200 ?were significantly improved. But the contact between p-type silicon and the former was ohmic contact,while the Schottky contact was formed in the latter. In order to obtain the excellent properties of ITO thin films and the ohmic contact, samples deposited at room temperature were annealed with different temperatures. The results showed that the ITO films presented a lowest resistivity of 5.4×10-4?·cm and a highest transmittance of 92.9% in the visible range after the heat treatment at 300?. Furthermore, with the additional post-annealing, the barrier heights between ITO films and p-type silicon were reduced. But the concact proerties became weak while the annealing temperature was above 300?. The contact showed a low value of barrier height and the specific contact resistance of 0.454 eV and 2.8×10-3?·cm2 with post-annealing at 300?. however, the contact changed to non-ohmic contact.In order to solve the problem of contact performance reduction after high temperature annealing, the TiW alloy was used as the diffusion barrier layer for preventing the oxidation at the interface between ITO thin film and p-type silicon. TiW alloy was deposited on the p-type silicon by RF magnetron sputtering and the ohmic contact between TiW alloy and p-type silicon was yielded when heated to 450? after holding for 60 mins at 250?. The contact was found to be non-alloying contact by analysising the microstructure of the samples.At last, the ITO/TiW double-layer thin films were prepared by magnetron sputtering. The photoelectric performances of ITO/TiW double-layer films were very easily effected by the metal layer and the ITO layer. The photoelectric performances of ITO/TiW double-layer films with different thickness of TiW layer and ITO layer were discussed.The optimum thickness of TiW layer and ITO layer were determined to be 8nm and 110 nm respectively. The crystallization properties of the double-layer films was found to be improved by the introduction of TiW layer. ITO(110nm)/TiW(8nm)/p-type silicon contact, with a specific contact resistance of 4.1×10-4?·cm2 was obtained in this thesis. It has been found that the introduction of TiW layer improved the properties of the contact between ITO thin film and p-type silicon significantly.