Scanning tunneling microscopy and potentiometry on a semiconductor heterojunction

The potential distribution across the cleaved end face of a forward-biased GaAs double heterojunction laser diode was mapped using scanning tunneling potentiometry. Space-charge regions next to the heterojunction interface as well as the electron-hole recombination region within the active layer are outlined with nanometer resolution. The carrier injection zone in the active layer is observed as a function of junction voltage.