Electronic properties for the C2v and Cs isomers of Pr@C82 studied by Raman, resistivity and scanning tunneling microscopy/spectroscopy

Fabrication and characterization of field-effect transistor device with C2v isomer of Pr@C82

“…The μ increases exponentially with increasing T above 230 K. The FET properties could not be observed below 230 K owing to very low I D of this device. Consequently, the FET properties found in the present study reflect the nature of the high-T (HT) phase of the C 2v -Pr@C 82 with small E gM and E gB above 230 K [13]. The μ value at 350 K reached to 2.5 x 10 -4 cm 2 V -1 s -1 , which was 50 times higher than that at 230 K. The lnμ vs. 1/T plot is shown in the inset of Fig.…”

“…FET device have been investigated above 150 K, and the clear FET properties were observed above 230 K, which corresponds to the semiconductor-semiconductor transition suggested from temperature (T ) dependence of resistivity [13]. The typical normally-off enhancement-type FET properties have been found by subtracting the bulk current I B from the drain current I D .…”

“…The high I B originates from the small mobility gap energy, E gM , of M@C 82 ; the E gM s of the C 2v isomer of Pr@C 82 and Dy@C 82 were estimated to be 0.29 and 0.20 eV, respectively, from the ρ -T plots [13,15]. Furthermore, the band gap energies, E gB s, of the C 2v isomer of Pr@C 82 and Dy@C 82 were determined to be 0.7 and 0.6 eV, respectively, from scanning tunneling spectroscopy [13,16], which were smaller than those of C 60 (1.8 -2.1 eV) and C 70 (2.2 eV) [17][18][19]. The T dependence of μ is shown in Fig.…”

Metallic phase in the metal-intercalated higher fullereneRb8.8(7)C84

“…The photoemission ͑UPS͒, 9 resistivity , 5,7,8 optical spectroscopy 10 and scanning tunneling spectroscopy ͑STS͒ ͑Ref. 11͒ showed a semiconductorlike behavior with small energy gap, E g , for M@C 82 where the valence of M is +3.…”

“…1 Recently, crystalline solid samples of metallofullerenes and higher fullerenes were obtained, and their structures have been studied by x-ray powder diffractions. [4][5][6][7][8] The crystals of M@C 82 ͑M = lanthanide atoms͒ showed a cubic structure of space group Pa3 ͓a = 15.78͑1͒ Å for Dy@C 82 , 15.78͑1͒ Å for the C 2v isomer of Ce@C 82 , and 15.74͑4͒ Å for the C s isomer of Ce@C 82 ͔.…”