ZnSe dot arrays are spontaneously formed on cleavage-induced GaAs (1 1 0) surfaces by depositing one ZnSe layer. Confinement of carriers to the dots is realized by the difference between the band gaps of strained ZnSe layer and strain-relaxed ZnSe dots. The formation of the dot arrays is demonstrated by surface observations and optical characterizations. Combining a composition modulation effect, ZnCdSe dot arrays and wires are realized by simply depositing one alloy layer. (C) 1998 Elsevier Science B.V. All rights reserved.