We present an overview and a comparison between three different methods of creating low density lateral In(Ga)As quantum dot molecules (QDMs) embedded in a GaAs matrix. Each of them is based on the use of nanoholes to control the dot nucleation site and generate the QDMs. The three methods used to create suitable nanoholes are: (1) In situ excess gallium droplet etching, where the nanohole shape is modified by overgrowth of a thin GaAs buffer to give QDM nucleation. (2) Ex situ electronbeam lithographic patterning and wet-etching, where the patterned nanohole size is critical for formation of QDMs. (3) In situ strain-selective etching of buried InAs quantum dots by AsBr 3 . The mechanisms of QDM formation, dependence on growth parameters, advantages and disadvantages of each technique and future challenges are discussed. . However, for quantum computation applications, interacting quantum systems are required [6]. One possible way to achieve this is to use the so-called 'quantum dot molecules' (QDMs).The most convenient method to realise optically active QDMs [7] is to take advantage of the vertical ordering which occurs between stacked layers of dots [8]. The quantum states in the two dots can be coupled by choosing a suitable spacer layer thickness and by applying an electric field to compensate differences in the dot sizes [9,10]. However, the lateral geometry is attractive due to the possibility of selectively contacting the single molecule and modulating the coupling strength between the dots [11][12][13][14].There are several ways to modify the substrate morphology in order to guide the growth of lateral QDMs. For example, QDMs have been grown on the facet edges of mounds [15,16], at the corners of pyramidal structures formed during selective area epitaxy [17] or on the edges and the bottom of nanoholes [11,12,[18][19][20][21][22].