Characterization of CdTe quantum dots grown on Si(111) by hot wall epitaxy

Abstract

We report on the growth and characterization of CdTe quantum dots on Si(111) by direct island nucleation. The samples were grown by hot wall epitaxy on Si(111) substrates treated with diluted HF solution only and the resulting hydrogen-terminated surface permitted the growth of good quality CdTe layers using substrate temperatures below 300 °C. The samples, grown at very low growth rates, were investigated by atomic force microscopy. Our measurements show that this system follows the Volmer-Weber growth mode, with nucleation of isolated CdTe islands on the Si substrate surface even for just 0.6 monolayers of evaporated material. As the growth proceeds, the density and size of quantum dots increase until the point at which they start to coalesce to form a uniform layer. We describe the size and density distribution of these islands as a function of growth time and substrate temperature. The results show that the Volmer-Weber growth mode can be successfully used to obtain self-assembled quantum dots of CdTe on Si, with reasonable size dispersion, using an inexpensive growth technique.