Two types of microwave emission from InSb

Two types of microwave emission from InSb plasma subjected to the crossed electric and magnetic fields were investigated experimentally. From the simultaneous measurements of Hall effect and microwave emission, the threshold condition of the one type of emission was obtained as(omega_{ce} tau_{e})^{2} cdot Delta n geq 3 times 10^{14}cm^-3, whereomega_{ce}, tau_{e}, andDelta nare 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 emission power of the other type of emission showed maximum value 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 by slight change in the low-current density region.