Quantum dots for optoelectronics

Semiconductor nanostructures (quantum dots and wires) promised enhanced optical gain and laser devices with negligible threshold current density an almost atomic-like energy levels. These expectations were based on the nature of the energy levels and their occupation probability. The reality was far from this and instead changes in the energy and momentum relaxation were said to result in a decreased light emission efficiency with decreasing dimensions. Quantum dots and wires fabricated by deep etching of III-V and IV-IV semiconductor quantum wells are used to illustrate the various aspects coming together relevant to device prospects. Novel approaches based on a delta-doping fractional layer and quasi-isoelectronic impurities are discussed. Suggestions are given for future work towards optoelectronic devices based on quantum dots and wires