The inhibition of negative resistance dipole waves and domains in n-GaAs

Expressions describing the growth and propagation of infinitesimal space-charge waves in the presence of a differential negative resistance are derived, and conditions for the inhibition of dipole waves and domains in -GaAs of resistivity greater than 10Ω-cm at 300°K are obtained. Thermoelectric effects are estimated and found to be small for carrier densities much less than 10¹⁵cm^-3. Taking the negative differential resistivity to be larger than the ohmic resistivity by a factor of 10²leads to 1) condition for inhibition of dipole waves: cm^-12) condition for inhibition of stable domains: cm^-2when = electron density and = specimen length. The relevance of these results to explaining the phenomena observed in amplifying crystals is pointed out. It is suggested that the condition for amplification is .