Structural and morphological investigation of the development of electrical conductivity in ion-irradiated thin films of an organic material

Journal Article · Sun Jan 15 00:00:00 EST 1984 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.333049· OSTI ID:5597686

Lovinger, A J; Forrest, S R; Kaplan, M L; Schmidt, P H; Venkatesan, T

Thin films of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) develop low electrical resistivity (<10/sup -3/ ..cap omega.. cm) after irradiation with 2-MeV Ar/sup +/ ions. Electron microscopy and diffraction show that vacuum-deposited films of this material consist, prior to ion-irradiation, of discrete crystalline grains (approx.20--50 nm diameter) in which the molecules are disposed closely parallel to the substrate (average inclination approx.10/sup 0/--15/sup 0/). Upon irradiation with up to approx.10/sup 14/ Ar/sup +//cm/sup 2/, the grains become progressively more defect-ridden and eventually amorphous. At that stage, the resistivity begins to decrease by approx.12 orders of magnitude at doses between approx.10/sup 14/ and approx.5 x 10/sup 16/ Ar/sup +//cm/sup 2/, while the intergranular boundaries become diffuse and the grains begin to merge. The temperature dependence of resistivity in this regime is as exp(const/T/sup 1//sup ///sup 2/), which is consistent with our morphological and structural results as it implies carrier hopping between conducting islands embedded in a nonconducting matrix. At the highest ion doses (>5 x 10/sup 16/ Ar/sup +//cm/sup 2/) the grains become connected into a rather uniform and featureless network akin to amorphous carbon, and the resistivity reaches its lowest value and becomes independent of temperature. The amorphous-carbon-like character of the highly irradiated material is evidenced not only by its diffraction pattern but also by its crystallization with a graphitic-type structure during annealing to 1200 /sup 0/C.

• Research Organization: Bell Laboratories, Murray Hill, New Jersey 07974
• OSTI ID: 5597686
• Journal Information: J. Appl. Phys.; (United States), Vol. 55:2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ORGANIC COMPOUNDS
PHYSICAL RADIATION EFFECTS
AMORPHOUS STATE
ARGON IONS
CARBON
COLLISIONS
CRYSTAL STRUCTURE
CRYSTALLIZATION
ELECTRIC CONDUCTIVITY
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
GLASS
GRAIN BOUNDARIES
HYDRIDES
INCLINATION
ION COLLISIONS
MEV RANGE 01-10
MORPHOLOGY
POST-IRRADIATION EXAMINATION
SILICON
SILICON OXIDES
SODIUM CHLORIDES
SUBLIMATION
THICKNESS
THIN FILMS
VACUUM COATING
VACUUM EVAPORATION
VERY HIGH TEMPERATURE
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
DEPOSITION
DIFFRACTION
DIMENSIONS
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY RANGE
EVAPORATION
FILMS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
IONS
MEV RANGE
MICROSCOPY
MICROSTRUCTURE
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RADIATION EFFECTS
SCATTERING
SEMIMETALS
SILICON COMPOUNDS
SODIUM COMPOUNDS
SURFACE COATING
360605* - Materials- Radiation Effects