Inhomogeneity Effects on the Oscillation Characteristics of “Long” Gunn Effect Devices

• Published in: Japanese Journal of Applied Physics 1968-01, Vol.7 (4), p.366
• Main Author: Hayashi, Toshiya
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.7.366

The effects of various parameters on the oscillation characteristics of “long” Gunn effect oscillators (from 0.2 to 2 mm) have been investigated under various controllable conditions. Almost all the samples prepared in this experiment showed the typical current-voltage characteristics of Gunn effect oscillators and clean coherent oscillations. Among the many samples tested, irregular ones were found; some did not oscillate coherently and some showed irregular current waveforms. These irregular oscillation characteristics were investigated using the samples with various inhomogeneities applied intentionally. The results of various investigations revealed that almost all irregular characteristics could be explained by the effects of various inhomogeneities in the samples. Namely, localized high conductive regions on the sample surface usually cause current waveforms of irregular shape, which has a number of “humps” between the well-known” spikes of Gunn-Effect oscillations. The location and number of the humps are well correlated with those of the high conductivity regions. High conductivity regions in the bulk also distort the current waveform. Mechanically damaged regions on the sample surface and in the bulk cause distorted current wave-forms and degrade coherency of oscillations. Strong aging effects have been seen in many irregular samples with various inhomogeneities.