A narrow photoluminescence linewidth of 21 meV at 1.35 mu m from strain-reduced InAs quantum dots covered by In0.2Ga0.8As grown on GaAs substrates

InAs quantum dots with size fluctuations of less than 4% were grown on GaAs using the self-assembling method. By covering the quantum dots with In0.2G a0.8As or In0.2Al0.8As, strain in InAs dots can be partly reduced due to re laxation of lattice constraint in the growth direction. This results in low -energy emission (about 1.3 mu m) from the quantum dots. The photoluminesce nce linewidth can be reduced to 21 meV at room temperature. This width is c ompletely comparable to the theoretical limit of a band-to-band emission fr om a quantum well at room temperature. Because the dots can be uniformly co vered by the strain reducing layers, factors that degrade size uniformity d uring coverage, such as compositional mixing or segregation, will be suppre ssed, allowing for an almost ideal buried quantum dot structure. (C) 1999 A merican Institute of Physics. [S0003-6951(99)02008-2].