Characterization of a IV-VI semiconductor structure consisting of a PbSe/PbSrSe multiple quantum well (MQW) active region between distributed Bragg reflectors grown by molecular beam epitaxy on a Si(111) substrate is described. Pulsed photoluminescence (PL) spectra exhibited interband electronic transition energies ranging linearly with temperature from 231.4 meV at 150 K to 299.4 meV at 300 K, while continuous wave (cw) PL spectra exhibited only the vertical optical cavity mode with emission varying between 299.2 meV at 150 K to 301.1 meV at 300 K. A maximum PL emission power of approximately 1.8 mW was obtained for cw diode laser pumping when the heat sink temperature was 200 K. Data are consistent with a localized epilayer heating effect of about 100 deg where the interband electronic transition energy is coincident with the vertical optical cavity mode. In spite of significant sample heating and associated thermal expansion mismatch stress, cw PL emission intensity was stable with no noticeable degradation in intensity after repeated measurements. These results show that IV-VI epitaxial layers on silicon are viable materials for fabricating reliable light emitters for on-chip optical interconnects.

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When illuminating four “mystery” vials of nanoparticle solution with a 405-nm light emitting diode (LED), four distinct colors related to the peak wavelength of fluorescent emission can be observed.1 This phenomenon perplexes high school physics students and leads to the subsequent exploratory question, “Why are the four vials emitting a different color light if they all contain the same material and are illuminated with the same light source?” That question gives students the opportunity to collect and analyze data, which leads to the development of the inherent scientific concept that the color of the emitted light depends on the size of the material (quantum dot) suspended in solution.

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