InGaAs/GaAs quantum wire structures were grown by low pressure metalorganic chemical vapor deposition by using selective area epitaxy. In 0.2 Ga 0.8 As/GaAs quantum wire structures were grown on a SiO 2 masked GaAs substrate. Quantum wire structures with sharp tips and smooth side walls were grown. We have grown InGaAs/GaAs quantum wire structures using variously opened width of the SiO 2 mask. Even though the opening widths of SiO 2 masked GaAs substrate were different, similar shapes of triangular structures were grown. Using various kinds of differently opened SiO 2 masked area, it would be possible to grow quantum wire structures with various thicknesses. The quantum wire structures are formed near the pinnacle of the triangular structure. Therefore, the fabrication of the uniquely designed integrated optical devices which include light emitting sources of multiple wavelength is possible.