Influence of doping on the threshold characteristics of GaAs lasers

A theoretical analysis is made of the influence of doping of the active region on the threshold and temperature characteristics of GaAs lasers. A comparison is made with the experimental data obtained for electron-beam-pumped lasers. A satisfactory description of the experimental results obtained for active elements with the full range of dopant concentrations requires an allowance for the influence of the absorption by carriers and of the Auger recombination of nonequilibrium carriers on the laser characteristics. Doping of the active region of a GaAs laser makes it possible to reduce the threshold pump current only in the case of short nonradiative lifetimes τ_nr. If τ_nr ≈ 1 ns, the optimal acceptor concentrations in p-type GaAs are 4 X 10¹⁸–10¹⁹ cm^–3 and the corresponding optimal concentrations of donors in n-type GaAs are (1–2) X 10¹⁸ cm^–3.