Local droplet etching of nanoholes and rings on GaAs and AlGaAs surfaces

We study the formation of nanoholes and rings on GaAs and AlGaAs surfaces by local droplet etching (LDE) with gallium and indium. The nanohole properties are tuned by variation in etching temperature and time as well as by the etchant. Nanoholes fabricated by In LDE are larger and have an about ten times lower density compared to Ga LDE, which allows the fabrication of nanoholes with ultralow density of less than 5 x 10(6) cm(-2). Furthermore, the nanohole borders are surrounded by distinct walls. The walls are crystallized from droplet material and serve as quantum rings with tunable size and band gap. (C) 2008 American Institute of Physics.