Fabrication of GaAs Quantum Dots on a Bilayer-GaSe Terminated Si(111) Substrate

We have developed a novel method to fabricate self-assembled quantum dots (QDs) of compound semiconductors on a Si(111) substrate using the so-called `droplet epitaxy' technique. In order to fabricate QDs on a Si substrate by droplet epitaxy, we examined the termination of a Si (111) surface with a bilayer-GaSe. This surface is formed by depositing 1 monolayer Ga on a Si(111)-7×7 surface and annealing in a Se flux at 520°C. Then Ga atoms are deposited to form Ga droplets on this surface, and the sample is annealed in an As flux to transform Ga droplets into GaAs QDs. It is revealed that GaAs QDs with a diameter as small as 10 nm and a height of 5 nm can be formed on the bilayer-GaSe/Si(111) substrate at a maximum density of 8.4×1010 cm-2. Using this method a new technique will be available to fabricate QDs of many kinds of compound semiconductors on the Si(111) substrate.