Observation of Plasma Density Waves in n-InSb in Transverse Magnetic Fields

Electron-hole plasma density oscillations in n-InSb have been investigated in transverse magnetic fields using a microwave probe technique. Experiments were done at 77°K and 210°K, using single pulses. The damped oscillations observed at 210°K have been identified as traveling density waves with frequencies ranging from 2 Mc–13 Mc, depending on the magnetic field intensity. The oscillations observed at 77°K were growing waves. The oscillations were identified as standing waves both in the longitudinal and transverse directions. Their frequency ranged from 20 Mc to 50 Mc depending on the magnetic field and the current strength. Both types of oscillations were seen in breakdown region of the current strength. Both types of oscillations were seen in breakdown region of the current-voltage curve. Incoherent waves, similar to noise, were observed above certain critical magnetic fields.