Thin Film Formations of Charge Transfer Complexes with Metallic Properties by Vacuum Deposition Method

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THIN FILM FORMATIONS OF CHARGE TRANSFER COMPLEXES WITH METALLIC PROPERTIES BY VACUUM DEPOSITION METHOD M.YUDASAKA*, *Materials Hodogaya-ku, **Institute

K.HIRONAGA*, Chemistry,

H.YAMOCHI**, K.NAKANISHI* AND G.SAITO** Yokohama National University, 156 Tokiwadai,

Yokohama 240, Japan for Soild State Physics,

7-22-1

Roppongi,

Minato-ku,

Tokyo,

Japan

ABSTRACT Thin films of a charge transfer pentaiodide ( TTF 7 I 5 , TTF:I 0 . 1 1 evaporation of TTF and obtained when substrate

complex, hepta-(tetrathiafulvalene) were prepared by double source iodine. Crystalline films of TTF:I 0 . 7 1 were 0 temperatures were kept between O°C and 25 C.

Orientation alignment of the rate of iodine. By controlling rate of iodine, substrates. It properties.

highly showed

),

crystalline films were affected by the substrate temprature and the

oriented crystalline strong dichroism

supply supply

films were grown on mica and anisotropic electrical

INTRODUCTION In utilizing fine characters of organic materials, one of the most potential technics is thin film formation by vacuum deposition. Different from inorganic semiconductors such aa Si and GaAs, however, organic materials have a disadvantage in evaporation methods; not a few organic materials decompose by heating before evaporation or sublimation. Polymers and charge transfer (CT) complexes are its examples. Because both polymers and CT complexes have a variety of fine properties, it is a valuable challenge to make their thin films by multi-source evaporation of starting materials (components). The authors have already shown that films of two dimensional copper phthalocyanine polymer and anthracene :pyromellitic acid dianhydride (PMDA) CT complex were available by this method; double source evaporation of Cu and tetracyanobenzene in the former case and that of anthracene and films of TTF:I 0 . 7 1 iodine by controlling that highly

PMDA in the latter[1,2]. are formed by the double substrate temperature

oriented TTF:I

0

.71

films can

be

This study shows that thin source evaporation of TTF and and supply rate of iodine and grown on mica.

EXPERIMENTAL TTF was purchased from Aldrich Chem. coevaporated in a pyrex glass chamber shown evaporation is also shown in Fig.1I. Inner quartz; upper was for TTF and the lower detected temperature of the crucible. The two by the Nichrome wire winded around them. In

Co.. TTF and iodine were in Fig.1. A crucible for TTF two cylinders were made of was for thermocouple which quartz cylinders were heated the film formation, 1-2mg of

TTF was evaporated by rasing the temperature of the crucible up to 5O~7OeC. Iodine was stored in an iodine source made of pyrex glass tube with one end closed and with the other end open (nozzle, 0.2mm•). The

Mat. Res. Soc. Syrup. Proc. Vol. 173. ©1990 Materaial

Research Society

138

diffusion pump

iO.N2

trap

KOH

column

liq N,

cfIII

trap

crucible for evaporation

Fig.l

Schematic illustrations source evaporation.

of

equipments

vacuum bttle for

TTF

and

iodine

double

closed end was dipped in a