Influence of the electron density in a gallium arsenide film on the cutofffrequency for the amplification of space-charge waves in thin-film semiconductor structures

A theoretical analysis is made of the cutoff frequency for the amplificatio n of space-charge waves in an n-GaAs thin-film semiconductor structure, tak ing into account the dependence of the drift velocity and the differential electron mobility on the electron density. It is shown that the dependence of the cutoff frequency on the electron density in the film has a maximum, which indicates that there is an optimum level of doping of the film for th e fabrication of higher-frequency functional devices utilizing space-charge waves in n-GaAs. (C) 1999 American Institute of Physics. [S1063-7850(99)31 02-X].