Study of the photoelectric properties of Ge quantum dots in a ZnSe matrix on GaAs

The current-voltage (I–V) and spectral characteristics of a photocurrent are studied at T=4.2 and 300 K for an unstrained GaAs/ZnSe/QD-Ge/ZnSe/Al structure with tunneling-transparent ZnSe layers and Ge quantum dots (QDs). Features such as the Coulomb staircase were observed in I–Vcharacteristics at room temperature and in the absence of illumination. An energy-band diagram of the structure is constructed based on an analysis of the experimental data. In the GaAs/ZnSe/QD-Ge/ZnSe/p-Ge transistor structure with a p-Ge channel and Ge-QD floating gate, the total current of the channel both increased and decreased under exposure to light with various spectra. These variations in channel current are associated with the capture of a positive and negative charge at QDs during different optical transitions. The charge accumulation changes the state of a channel at the heterointerface from depletion to inversion and either decreases or increases the total current.