Cooperative growth of nano-islands on Si(1 0 0) surface

By setting up two low temperature regions on a terrace of a vicinal Si(1 0 0)-2 × 1 surface, we have studied growth of nano-islands in the two regions using a kinetic Monte Carlo simulation. At first two islands are formed and grow independently without any supply of atoms from the outside. As the growth proceeds further, two islands are connected with each other by forming a bridge region. After the connection, the growth changes dramatically showing a competitive mode in one stage and a cooperative mode in the other. Two islands grow cooperatively in a sense that a larger island ceases to grow and waits until the size of the other smaller island becomes similar to that of the larger one. When two islands become similar in size, one of the islands grows faster than the other competitively, by accumulating atoms from then smaller one. The origin of the growth mode is analyzed.