Observation of resonant tunneling through a quantized state in InP quantumdots in a double-barrier heterostructure

A direct spectroscopic signature associated with the quantized state of the charge carriers in three-dimensionally confined InP quantum dots (QDs) is reported using a ballistic electron emission microscopy (BEEM)/spectroscopy technique. The self-assembled InP QDs are sandwiched in an AlInP double-ba rrier heterostructure. The excellent nanometer-scale lateral resolution of the BEEM technique is used to investigate the current transport mechanism b y the direct injection of electrons into a single quantum dot. The BEEM spe ctra taken on and off the dot revealed the presence of a localized state at around 0.1 +/- 0.02 eV above the ground state. (C) 2000 American Institute of Physics. [S0003-6951(00)00734-8].