Self-assembled quantum dot transformations via anion exchange

We report the effect of dissimilar anion anneals on the properties of layered quantum dot structures exhibiting vertical self-organization. Such anneals may provide an additional means of controlling dot properties, such as composition, size, and position. In addition, the modification of surface strain is critical to the subsequent nucleation of dots after the initial seed layer. Anion exchange may modify the strain at the semiconductor surface. We find that the effects of P2 and As4 anneals on InAs quantum dot size distributions are different. P2 anneals at relatively high temperatures (350 °C) can cause the loss of the three-dimensional morphology due to surface exchange. P2 anneals at lower temperatures (300 °C) appear to improve the uniformity of the dot size distribution. This behavior is not observed for anneals under As4. The dot size uniformity decreases by annealing dots under As4 at 300 °C.