On Gunn Instability in Two-Dimensional Semiconductors

Abstract

The instability associated with negative differential conductivity in two-dimensional (2-D) semiconductors such as inversion layers of MOSFET is discussed. The space-charge accumulation exhibits considerably different features from those in bulk materials, because of the different k -dependence of the growth rate of space-charge Fourier components; the growth rate is proportional to k in 2-D, while it is independent of k in 3-D. It is deduced that the layer must finally be covered with space-charge waves, e.g., of k ≃10 4 ∼10 5 cm -1 in the n-inversion layer of Si.