Rubrene single crystal field-effect transistor with epitaxial BaTiO3 high-k gate insulator

High quality BaTiO3 thin-film epitaxially grown on a Nb-doped SrTiO3 (BTO/Nb-STO) substrate by a laser ablation technique is employed as a high-k gate insulator for a field-effect transistor of a rubrene single crystal in order to search for the possibility of high carrier accumulation. The high dielectric constant ϵ of 280esu for the prepared BaTiO3 thin-film accumulates 0.1holes∕rubrene-molecule, which is 2.5 times as high as the maximum carrier number of 0.04holes∕rubrene-molecule attained in the case of SiO2. This is the highest carrier number so far obtained in organic field-effect transistors (FETs). Other important parameters of rubrene single crystal FETs on BTO/Nb-STO are described in comparison with those on SiO2/doped-Si.