Effect of in situ photoexcitation of n-type Si as a result of ion implantation at low doses on the formation of radiation defects

The effect of in situ photoexcitation of the electronic subsystem of a semiconductor as a result of implantation of low ion doses on the formation of complexes of radiation defects in n-type Si is investigated by the DLTS method. The n-type Si samples were irradiated with 150-keV O ₂ ⁺ and N ₂ ⁺ ions at the same dose 10¹¹ cm⁻² and Ar⁺ ions at doses 7×10¹⁰ and 2×10¹¹ cm⁻². With the exception of the latter case, the ion energy and dose were chosen so as to produce approximately the same number of initially displaced Si atoms and the same depth distribution of such atoms from the target surface. The temperature of the n-type Si samples during irradiation was 300 or 600 K. Photoexcitation of the semiconductor was performed using UV radiation with various power densities. It is shown that radiative heating of the samples during ion implantation suppresses the formation of radiation-defect complexes, while photoexcitation of n-type Si, in contrast, intensifies their formation. It is found that the effect of illumination increases with decreasing ion mass and with increasing target temperature. The effect of UV illumination on defect formation in n-type Si as a function of sample temperature during ion implantation is established. It is found that the density of divacancies in n-type Si saturates with increasing illumination intensity. Fiz. Tekh. Poluprovodn. 33, 537–541 (May 1999)