INVESTIGATION OF CdTe QUANTUM DOTS SYNTHESIS TECHNOLOGY FEATURES IN COLLOID SOLUTIONS BY PHOTOLUMINESCENT SPECTROSCOPY AND SURFACE PLASMON RESONANCE REFRACTOMETRY

Abstract

Effect of activation current variation in the synthesis of quantum dots (QD) of cadmium telluride in colloidal solutions on the change of emission spectra of photoluminescence (PL), the average size of QD and the change in the angular position of refractometric characteristics of surface plasmon resonance (SPR) was studied. The activation current was changed from 0.1 to 0.6 A in steps of 100 mA. For comparison, also performed the synthesis of cadmium telluride QD in colloidal solutions with a change in the duration of the synthesis in the range from 1 to 5 minutes in increments of 1 minute. The average QD size of cadmium telluride was determined by the peak values of the measured PL spectra of the corresponding colloidal solutions according to the modified Bruce formula. The response of the SPR sensor constructed according to the Kretschman scheme was defined as the angular shift of the minimum of the measured refractometric characteristics of the SPR when replacing deionized water with the studied colloidal solutions. The results of the study showed that the increase in the activation current in contrast to the increase in the duration of the synthesis led not only to a decrease in PL intensity, but also to its increase at low currents, which may be due to "electropolishing" of the quantum dot surface. Both technologies for the synthesis of quantum dots were characterized by the presence of slow growth processes, which was associated with the thermodynamics of nucleation processes and manifested in the form of saturation regions on the graphs of PL peak and minimum refractometric characteristics of SPR from synthesis duration and activation current. At different durations of quantum dot synthesis, a dependence (correlation coefficient -0.9992) was established between the response of the SPR sensor and the spectral position of the PL maximum, which was approximated by a linear function with a matching coefficient R 2 = 0.998. The results of the study showed that the use of variation of activation current in stabilizing the duration of synthesis is the dominant condition for creating high-emission light-emitting and light-converting semiconductor systems based on cadmium telluride QD, because with variation of activation current PL intensity was 431.9 abs., 4 times higher than for the case of variation in the duration of synthesis, namely 181.2 abs.one. The results of the study can be used to optimize the technology of manufacturing QD of cadmium telluride with predetermined characteristics.