Electrical conduction in gold nanoparticles embedded indium oxide films: a crossover from metallic to insulating behavior

Electrical conductivity of indium oxide and gold nanoparticles incorporated indium oxide films grown by dc sputtering have been studied in the temperature range 1.5 to 300K. Films with 0, 6 and 12% gold nanoparticle volume fraction exhibit metallic nature in the temperature interval 1.5 to 20K, with conduction being governed by electron-electron interaction. Films with 20% gold nanoparticle volume fraction showed insulating nature and the conduction was governed by variable range hopping mechanism in the temperature range 1.5 to 50 K. Furthermore, a crossover from Efros-Shklovskii to Mott type was observed around 15 K. The transition from metallic to insulating nature in spite of the larger gold nanoparticle volume fraction is attributed to the inhibition of oxygen vacancies by Au species during film growth. At higher temperatures, all films exhibit activated conduction.