Design of quasi-lateral p-n junction for optical spin-detection in   low-dimensional systems
  A technology is reviewed which allows one to produce quasi-lateral 2D electron and hole gas junctions of arbitrary shape. It may be implemented in a variety of semiconductor heterostructures. Here we concentrate on its realization in the GaAs/AlGaAs material system and discuss the possibility to use this structure for optical spin detection in low-dimensional systems. 
B. Kaestner, D. G. Hasko and D. A. Williams