Quantum wires are fabricated by the growth of the AlGaAs system on vicinal (110) GaAs substrates misoriented toward (111)A. It is concluded that during the growth of AlGaAs, composition modulation occurs on the large-step structure almost independently of the temperature, while the large-step structure is formed by the growth only below a transition temperature. The photoluminescence (PL) from a single quantum wire is observed with a much narrower spectral width as compared with the PL from multi-quantum wires.