Doping of 5,10-dimethyl-5,10-dihydrophenazine ((Me)(2)P) to a 2-octadecyl-7,7,8,8-tetracystnoquinodimethane (C(18)TCNQ) LB film has been examined in a vapor phase, and it is found that the mixed-stack charge-transfer (CT) complex of (Me)(2)P and C(18)TCNQ in a quasi-ionic phase is formed by the doping. The (Me)(2)P-C(18)TCNQ LB film is found to consist of many platelet-like microcrystal domains with a well-ordered layered structure of thickness 3.31 nm. In the high-resolution atomic force microscopy measurements, a two-dimensional periodic molecular arrangement is observed. The period is 0.96 nm x 0.83 nm and the angle between the axes is 59 degrees. By polarized electronic absorption spectroscopy it is confirmed that the molecular arrangement consists of the alternatively stacked array of (Me)(2)P and C(18)TCNQ. The doping in the vapor phase is very effective for the preparation of highly crystallized and oriented thin films of mixed-stack CT complexes.