Electrical conduction phenomena of $C_{22}$--quinolium(TCNQ) langmuir-blodgett films under the high-electric field

$C_{22}$-quinolium(TCNQ) LB막의 고전게 전기전도 현상

  • 신동명 (홍익대학교 화학공학과) ;
  • 김태완 (홍익대학교 물리학과) ;
  • 홍언식 (홍익대학교 전자전산기공학과) ;
  • 송일식 (홍익대학교 전기제어공학과) ;
  • 유덕선 (홍익대학교 과학기술연구소) ;
  • 강도열 (홍익대학교 전기제어공학과)
  • Published : 1994.03.01

Abstract

Electrical conduction phenomena of $C_{22}$-quinolium(TCNQ) Langmuir- Blodgett(LB) films are reported through a study of current-voltage(I-V) characteristics along a perpendicular direction. The I-V characteristics were investigated by applying a step or a pulse voltage to the specimen as well as changing temperatures in the range of 20-250[.deg. C] It show an ohmic behavior in low-electric field, and a nonohmic behavior in high-electric field. This nonohmic behavior has been interpreted in terms of a conduction mechanism of space-charge limited current and Schottky effect. When the electric field is near the strength of 10$_{6}$ V/cm, there occur anomalous phenomena similar to breakdown. When step or pulse voltage is applied, the breakdown voltage shifts to the higher one as the step or pulse time width becomes shorter. To see the influence of temperature, current was measured as a function of temperature under the several bias voltages, which are lower than that of breakdown. It shows that the current increases to about 103 times near 60-70[.deg. C], and remains constant for a while up to around 150[.deg. C] and then suddenly drops. We have also performed a DSC(differential scanning calorimetry) measurement with $C_{22}$-quinolium(TCNQ) powder in the range of 30-300[.deg. C]. These results imply that the anomalous phenomena occuring in the high electric field are caused by the electrical and internal thermal effect such as a joule heating.ating.

Keywords