CORNELL UNIV ITHACA NY SCHOOL OF ELECTRICAL ENGINEERING
The harmonic content of solid state GaAs Gunn effect oscillators has been experimentally investigated using a lamellar grating far-infrared interferometer. The experiment has shown that power as low in frequency as 6 GHz can be modulated by the grating and that the instrument can be used in this frequency range with appropriate high-pass filters and above 60 GHz without filters. A number of the experimental difficulties encountered and instrumental modifications made to reduce the low frequency operating limit are discussed. A high dc bias mode of operation of a high-purity n-type epitaxial GaAs detector was discovered and its properties were investigated. This sensitive, broad-band detector, which had a response time of about 20 nsec, was used for the harmonic content measurements. In general, only a few harmonics of the X-band Gunn effect devices were observed and these died off rather rapidly. The experimental results were in fairly good agreement with theoretical predictions and indicate that the relative harmonic content increases with nf. No definite correlation between harmonic content and bias voltage was found. The highest frequency at which power was observed was 82 GHz, a tenth harmonic. Thus the results do not contradict the predicted upper frequency limit of operation for these devices. Author
Final technical rept. 1 Oct 67-31 Oct 70,
See also Volume 1, AD-883 604L and Volume 3, AD-883 608L.