Enhanced Carrier Diffusion Associated with the Instability in Germanium Slice

Abstract

Enhanced carrier diffusion associated with the density wave instability due to the gradient of carrier density in germanium slice was estimated at 77°K from the observations of (1) the distribution of carrier density along the direction of the thickness of the slice in the transverse magnetic field and (2) the transient time necessary for the decrease of the gradient of carrier density. The results show that when the instability occurs, the ambipolar diffusion constant Da of hot carriers becomes very large, i.e., Da∼105 cm2/sec (at 700 V/cm) which is larger about an order of magnitude than that before the instability occurs. The phenomenon is discussed in conjunction with the current oscillation (wherein microwave emission was also observed) in germanium slice, as well as the frequency response of the devices relative to the magnetic barrier layer effect.