| dc.description.abstract | The aim of this research is to investigate the photocurrent characteristics of Ag particles/In2O3 Ohmic contact. The Ag particles/In2O3 Ohmic contact was fabricated by Ag-In alloy film with different composition heat-treating at 800 oC in oxygen ambience. The contact of Ag and In2O3 is confirmed be Ohmic contact. Photocurrent characteristics of Ag particles/In2O3 composite structure was researched by using illumination light with different photo energies. Since the photo-carrier generation is determined by the optical generation rate and recombination lifetime (Δn = geτr), the discussion will be focused on these two factors.
The results show that under UV-light illumination, the photocurrent of pure In2O3 thin film with the oxygen adsorption could be enhanced. The mechanism has been reported that surface oxygen adsorption would induce a surface build-in electric field and enhance the life-time of excited electron-hole pairs, which would enhance life time. However, the photocurrent of the Ag particles/In2O3 fabricated by oxidized Ag70In30 alloy film is two orders higher than that of the pure In2O3 thin film. Since the matrix of these two samples are both In2O3, and heat-treat in oxygen ambience at same temperature in the same time, We assume that the effect of the surface oxygen adsorption on the recombination lifetime (τr) is similar to the In2O3 thin film heat-treated at 800 oC and the Ag particles/In2O3 composite structure. Then, we discuss that if the optical generation rate (ge) cound be enhanced by Ag particles.
Hot electron effect of Ag particles can transferring the accumulated energy from incident light to electrons by non-radiative decay, and this process would produce highly energetic electrons, which may have sufficient energy to transport to the conduction band of In2O3 and provide excess carriers for In2O3. Therefore, the photo energy is not necessary higher than the band-gap energy of In2O3, and this was checked by illumination light with the photo energy lower that the band-gap energy of In2O3, the blue-light, green-light, and red-light. And, the photocurrent was also measured.
According to the results, photocurrent is observed that no matter the photo energy of incident light is higher or lower than the band-gap energy of In2O3. It can be proved that the hot-electron effect is applied on the Ag particles/In2O3 Ohmic contact structure, which would cause photo-excited electrons of Ag particles transferr to the conduction band of In2O3, and the excess carrier can be measured as photocurrent. | en_US |