Collision dominated instabilities in InSb

Summary form only given, as follows. Experimentally, noise emissio from InSb has been observed when an electric field is applied to it in the presence of a magnetic field at 77°K in n-type InSb. More recently, the experiments at 200°K has been repeated in essentially intrinsic InSb, where far stronger oscillations were observed. A theory has been carried out which predicts that when electrons and holes drift with their velocities at an angle to each other, in the presence of a transverse magnetic field, there can be an instability even in a collision-dominated medium. This is what would occur near a contact which shorts out the Hall field in a medium such as InSb, where the electrons have a large Hall angle. The theoretical predictions for the threshold field appear to be in reasonable agreement with a number of experiments, those of Eidson and Kino, those of Musha and those of Suzuki, provided it is assumed that there is hole injection. The experiments carried out at 200 0K were done using p-type InSb, so the number of holes present was known. The agreement between theory and experiment is fair, but not perfect. The predicted threshold magnetic and electric fields are of the right order of magnitude and the shape of E versus B curve for threshold is correct. This mechanism does not require a phonon interaction and is entirely due to the interaction between electrons and holes in a collision-dominated medium. Furthermore, no generation of extra carriers, nonuniform density or finite temperature is required to explain the results.