Systems for display, transmission and memroy of information with the help of light are widely used. Therefore, it is necessary that the optolelectronic devices, their essential components, have high performance which can be obtained by the monolithic integration of optoelectronic devices and electronic devices to form functional optoelectronic integrated circuits. In this thesis, first, overview, brief history and classifications of OEIC are described. The characteristics of various integration structures, integrable lasers and high speed electronic devices are discussed. Based on these considerations, a new OEIC design method is proposed in which the essential layouts of the electronic devices are placed first, and then epilayers for the optoelectronic devices are selectively grown on the opennings in the mask which covers the layouts of the elecgronic devices. Selective epi-growth, vertical mirror formation and Zn diffusion, which are the basic technologies for the fabrication of OEIC, are studied in detail. $\circ$ Trench Attached Selective LPE (TASLPE) technique is proposed and proved to be useful for the uniform epi-growth and the fabrication of the index-guided laser diode. $\circ$ Two Step Etching Technique (TWOSET), a simple wet chemical etching method, is developed for the formation of the vertical mirror of the integrated lasers, and tandem lasers are successfully fabricated by this method. $\circ$ Zn diffusion into GaAs through $Al_{0.3}Ga_{0.2}As$ is analyzed, and proved by experiment. A new diffusion method, Double Diffusion Process (DDP), is proposed. It is shown that with this technique it is possible to control two different diffusion fronts separately. A P-Gate SCR laser is successfully fabricated by adopting DDP. In order to integrate comprehensively the proposed OEIC design method and the developed basic technologie, a new vertical OEIC, which contains a vertical JFET below the high index-guided laser diode, si proposed and fabricated experim...