Growth of InAs/InP(0Â 0Â 1) nanostructures: The transition from quantum wires to quantum dots

The evolution of InAs nanostructures grown by solid source molecular beam epitaxy on InP(0 0 1) substrates has been studied by atomic force microscopy (AFM), with specific emphasis on the effects of the incident V:III flux ratio. Wire structures oriented along 〈1¯10〉 are generally formed at moderate V:III flux ratios (∼10:1). AFM images show that the wires are generally kinked with small three-dimensional (3D) islands appearing at the kinks. Higher V:III ratios (>100:1) lead to an increase in the number of kinks and the formation of much larger 3D features. By contrast, low V:III ratios (∼2:1) favour the formation of small 3D islands (quantum dots) with densities of ∼5×1010 cm−2. The results indicate that it is possible to produce arrays of InAs/InP quantum wires or quantum dots through careful control of the growth conditions.