GIANT TEMPERATURE RESONANCES OF NOISE IN SUBMICRON QUANTUM-WELL STRUCTURES

We show that excess noise in micron-sized samples fabricated from Si-d oped GaAs/GaAlAs quantum wells and heterostructures is a strong non-mo notonic function of temperature with several sharp peaks below room te mperature. The noise power at the peaks exceeds the background noise b y several orders of magnitude. The observed behaviour represents a cla ssical noise source where only a single type of switching defect with a well-defined activation energy is present. We attribute the resonanc es to deep metastable donors and provisionally identify one of the don ors as the known DX-centre in GaAs and GaAlAs.