Rubrene single crystal field-effect transistor with epitaxial BaTiO ₃ high- k gate insulator

High quality BaTi O3 thin-film epitaxially grown on a Nb-doped SrTi O3 (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 of 280 esu for the prepared BaTi O3 thin-film accumulates 0.1 holesrubrene-molecule, which is 2.5 times as high as the maximum carrier number of 0.04 holesrubrene-molecule attained in the case of Si O2. 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 Si O2 /doped-Si.