Local density of states mapping of a field-induced quantum dot by near-field photoluminescence microscopy

We have described near-field photoluminescence microscopy of a field-induced quantum-dot structure based on a Be- δ -doped GaAs-Al _1-xGaxAs single heterojunction with a surface square mesh gate. The local density of states in the field-induced quantum dot was mapped by measuring the spatial distribution of the near-field photoluminescence intensity, because the photoluminescence spectrum owing to the recombination of holes bound to Be accepters with electrons in an electron gas contains information on the electronic density of states. Experimentally, we observed that the electrons confined in lower energy states spatially localize in a field-induced quantum dot.