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

Journal Article · Sun Jan 15 04:00:00 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), Journal Name: J. Appl. Phys.; (United States) Vol. 55:2; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

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