We have studied the OMCVD growth of GaAs/AlGaAs quantum well heterostructures on non-planar substrates in the temperature range of 625 to 750°C. The lateral variation in layer thickness and other growth features were found to depend not only on the growth temperature but also on the aluminum content of the layer. An example of the application of this technique of producing lateral thickness variations in quantum well heterostructures to a quantum well semiconductor laser is given. A unique feature of this laser is the formation of a quantum-wire-like crescent shaped active region at the center of a two-dimensional optical waveguide.