A theoretical investigation of the stationary behaviour of transferred electron devices with GaAs-type velocity-field characteristics has been carried out on an electron concentration field plane. Solutions over a wide range of doping concentration which satisfy the boundary conditions forn+-n-n+structure can topologically be obtained using the method of the field of directions which was introduced by Böer and associates. The use of this method enable us not only to understand and predict a variety of device phenomena based on formation of an anode domain, but also to see the concept of instability.