The results of a study of a structure with a single array of InAs quantum d
ots in a GaAs matrix using capacitance-voltage measurements, deep-level tra
nsient spectroscopy (DLTS), photoluminescence spectroscopy, and transmissio
n electron microscopy are reported. Clusters of interacting bistable defect
s are discovered in GaAs layers grown at low temperature. Controllable and
reversible metastable populating of quantum-dot energy states and monoenerg
etic surface states, which depends on the temperature and conditions of a p
reliminary isochronal anneal, is observed. This effect is associated with t
he presence of bistable traps with self-trapped holes. The DLTS measurement
s reveal variation of the energy for the thermal ionization of holes from s
urface states of the InAs/GaAs heterointerface and the wetting layer as the
reverse bias voltage is increased. It is theorized that these changes are
caused by the built-in electric field of a dipole, which can be formed eith
er by wetting-layer holes or by ionized levels located near the heterointer
face. (C) 1999 American Institute of Physics. [S1063-7826(99)00702-4].