OPTICAL-PROPERTIES OF WIRE AND DOT STRUCTURES FOR PHOTONIC APPLICATIONS

The realization and physical investigation of wire and dot structures will be reported. Fabrication requirements for low dimensional semiconductor structures will be discussed for masked implantation enhanced intermixing technique (MIEI) and for dry etching technique with subsequent overgrowth. With dry etching technique wire structures down to 30 nm could be achieved. With MIEI technique wire structures down to 40 nm and dot structures down to a radius of 100 nm could be achieved. A quantum efficiency of 0.84 can be obtained for etched and overgrown wires at 65 nm and an increase of the quantum efficiency of more than 3 orders of magnitude compared to as etched wires could be demonstrated. Strong size dependent carrier capture and carrier relaxation effects can be demonstrated in wires. The observed carrier relaxation in 1D semiconductors is strongly reduced if wires become smaller. Band filling effects and band gap renormalization of the 1D electron-hole plasma (1D EHP) could be determined over a wide range of wire widths. Appreciable size effect of the 1D EHP can be demonstrated for both etched and implanted wires. The experimental band gap renormalization of the 1D EHP appears weaker than for 2D EHP as expected and is stronger than the theoretical 1D band gap renormalization for an ideal 1D EHP due to its quasi 1D dimensionality. © 1992.