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The pressure dependences of the electrical conductivity and Hall coefficient have been studied for GaAs and AI,Ga, _,As ( x = 0.20 and 0.25) heavily doped with Te. The results obtained show that for a GaAs crystal the resonant donor level related to Te is located approximately 0.45 eV above the conduction band minimum. The effect of persistent photoconductivity observed at high pressures proves t h e DX-like character of this donor state. Comparison of the data on the energetic position of the DX level illustrates its strong chemical energetic dependence (for Si, Sn and S dopants an E,, value of around 0.3 eV has been reported previously). It appears that Te represents an impurity which is very suitable for testing the microscopic models of the DX centre. Studies of processes of the thermal recovery after high pressure freeze-out of electrons on the metastable states of the DX centres clearly demonstrate the multicomponent structure of t h e DX state in AlGaAs samples.

The influence of pressure, temperature, composition and components ratio of laser mixture on the discharge properties, gain and lasing parameters of pulsed electron beam controlled discharge N2O laser with the output energy more then 100 J and efficiency about 10 % has been studied experimentally and theoretically. The excitation efficiency in EBCD and relaxation constant of N2O laser levels have been estimated