Double barrier heterostructures of Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As/GaAs are studied. The presence of a quantized level in the well is confirmed by the observation of a region of negative differential resistance (NDR) in the current-voltage (I-V) characteristics of the heterostructures. A spectrum analyser and a network analyser are thus used to measure the oscillator properties of the samples and to investigate the effects of the external circuit on these properties and on the I-V characteristics. For the sample with AlAs barriers, electron oscillations, of frequency greater than 1 GHz, are measured at room temperature; the observation of these frequencies depends on the matching of the impedances of the external circuit to the device under test. Photoconductivity spectra and photocurrent-voltage (PC-V) characteristics at fixed wavelengths are measured in order to study the effects of light incident on the sample. I-V measurements are carried out in a quantizing magnetic field parallel to the tunneling current. With increasing magnetic field, the voltage periodic structures are shifted to higher bias positions at a similar rate of change. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/6003 |
| Date | January 1989 |
| Creators | Richard, Paul G. |
| Contributors | Fortin, E., |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 157 p. |
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