Parametric instabilities of both space charge and electromagnetic waves in GaAs semiconductors

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This paper deals with the non-linear parametric effects on both space charge waves (with phase velocity equal to the electron drift velocity) and electromagnetic waves (with phase velocity equal to c1 , where c is the permittivity) in GaAs semiconductors. If an external electric field is applied, a negative differential conductivity is obtained. Under these conditions, the electron velocity is a function of the electric field, which is given by E =E0 + E , where E0 is the constant part and is the variable part. The analysis of the parametric interaction of the waves in the GaAs semiconductor is realized considering both the Maxwell's equations and the velocity function. The one-dimensional model and the axis z, as the spreading wave direction, are chosen. The analyses of instabilities are realized -by using the Blombergen's Method. The instability efficiency is determined by the velocity, V0, the differential mobility, jiD; and the non-linear parameter, VD;by means of the temperature model of the Gunn Effect. The efficiency is good if the interaction parameters As and as, which are obtained from the system formed by the Maxwell's equations and the velocity function, are optimal. At the critical field value, Ecrit, the mobility changes its sign and becomes negative, as a result, there are obtained non-linear and linear parametric instabilities of the interactions at fields E2Ecrjt. The nonlinear parameter Vd obtains a maximum at the optimal value of electric field, where all linear processes are very effective.