Two Types of Microwave Emission from InSb

Two types of microwave emission, namely noise type and resonance type emission, from InSb plasma subjected to crossed electric and magnetic fields were investigated experimentally. From the simultaneous measurements of Hall effect and microwave emission, the noise type emission was found to be observable above some thresholds of the applied magnetic field and the density of electron-hole plasma. The threshold condition was obtained as (ω c e τ e ) 2 · Δ n ≥3×10 14 cm -3 , where ω c e , τ e and Δ n are electron cyclotron frequency, relaxation time and electron-hole pair density, respectively. It was also found that the `Hall' mobility showed anomalous decrease above the threshold. The power of the resonance type emission shows maxima at several values of the applied magnetic field lower than the threshold of the noise type emission. These characteristic magnetic fields were not influenced by current density except slight change in the low current density region.