Change of Bandgap Energy in Quantum System of Nanolayer on Silicon

Abstract

In the quantum system of nanolayer (NL) on silicon, the bandgap energy obviously increases with the decrease of NL thickness, where the quantum confinement (QC) effect plays the main role as the thickness of Si NL changes along with (100), (110) and (111) directions, respectively. And the simulation result demonstrated that the direct bandgap can be obtained as the NL with (001) direction is thinner than 10 nm on Si surface. However, it is discovered in the simulated calculation that the QC effect disappears as the NL thickness arrives at the size of the monoatomic layer, in which its bandgap sharply decreases, where the abrupt change effect in bandgap energy occurs near-ideal 2D-layer. In the experiment, we fabricated the Si NL structure by using electron beam irradiation and laser deposition methods, in which a novel way was used to control the NL thickness by modulating irradiation time of the electron beam. The new effect should have a good application on a photonic-electronic chip of silicon.