source materials respectively in the retainers 5 and 6 and evacuating the inside of the tube 1 to an appropriate pressure the tube 1 was hermetically closed and heated by means of the heater 3 the heating was continued approximately for an hour as a result d x a y complex crystals of 100 u02dc 200 u03bcm width and 1 mm height were grown on the teflon substrates 8 the total weight of the crystals were approximately 100 mg the d x a y complex crystals thus formed were conductive but exhibited characteristics of a semiconductor with a ratio of x y u2260 1 1 these crystals were thermal annealed at 100 u00b0 u02dc 150 u00b0 c for 2 hours in a muffle furnace then desired charge transfer complexes were obtained whose electric conductivities are shown below although in the above example the tube 1 was hermetically sealed off the donor and acceptor can be supplied into an open tube in fluid forms from bubbling devices in which liquids containing donor and acceptor sources respectively are bubbled by an inert gas the fluid donor and acceptor sources are mixed in the open tube so that complex crystals are grown on the substrate although in the structure shown in fig2 the substrate on which crystals grow is located to be heated the location may be a cooling location in some particular cases referring to fig3 a second embodiment of the present invention will be described.