OPTICALLY-PUMPED LASING OF DOPED ZNSE EPITAXIAL LAYERS GROWN BY METAL-ORGANIC VAPOR-PHASE EPITAXY

Laser action in undoped, nitrogen and chlorine doped ZnSe epitaxial la yer has been achieved and investigated at pulse optical excitation by N-2 laser radiation with a frequency of 1000 Hz from liquid nitrogen t emperature up to near room temperature at 270 K. The highest value of ZnSe laser energy and power were E = 5 x 10(-8) J and P = 5 W at I-exc = 800 kW/cm(2). The laser line positions in doped samples ZnSe:Cl (la mbda = 450.7 nm) and ZnSe:N (lambda = 451.2, 451.5, 452.0 and 455.5 nm at different excitation intensities) are shifted to the high waveleng th side compared to undoped ZnSe (lambda = 449.8 nm). It was shown tha t doping ZnSe with both acceptor or donor impurities as well as using a ZnMgSSe barrier layer between the ZnSe layer and the substrate is fa vourable to increase PL efficiency and to decrease the laser threshold . The lowest threshold value (130 to 150 kW/cm(2)) was achieved in ZnS e:N grown with hydrogen carrier gas. The results obtained from measure ments of the laser line positions as well as from the evaluation of th e nonequilibrium carrier concentration proves that the ZnSe lasing mec hanism under excitation by the N-2 laser radiation is the recombinatio n in an EHP. We found that under high excitation intensity a degradati on of the excited region of the ZnSe takes place causing a decrease of the emission intensity. Under lower excitation power the PL intensity enhances during the course of irradiation.