Emission Kinetics from PbSe Quantum Dots in Glass Matrix at High Excitation Levels

Abstract

The photoluminescence dynamics of PbSe quantum dots in a glass matrix (PbSe:Glass) is investigated at high excitation levels. Up to 470 meV blue‐shifted emissions are observed, which are assigned to excited‐state emission populated by carrier accumulation. Rapid photoluminescence decays of ∼25–40 ps are observed. Together with a threshold‐like dependence on excitation, even at room temperature, this component is tentatively attributed to amplified spontaneous emission. The absence of stimulated emission from the ground state and the overall higher threshold compared to PbS:Glass suggest that there are more intrinsic restrictions on the use of PbSe:Glass as a laser material than for PbS:Glass.

Stimulated emission at 1.54 μm from erbium/oxygen-doped silicon-based light-emitting diodes

“…2g). These features along with the FWHM narrowing suggest that amplified spontaneous [21,23,24] (or stimulated [33,34]) emission occurs in our Si LEDs. The emission cross-section can be thus estimated by the following equation [30,39],…”

“…Moreover, a super-linearly growing electroluminescence (EL) is obtained with a slope efficiency beyond 2 even at room temperature. The low threshold of ~6 mA (~0.8 A/cm 2 ) [19,20], the super-linear EL integral intensity [21][22][23], the narrowing full width at half maximum (FWHM) [24,25], and the Gaussian-like spatial emission distribution [26,27], as well as the fast radiation recombination lifetime [28][29][30][31], confirm the presence of stimulated emission involving transitions related to the Er 3+ [32][33][34]. Time-resolved PL (TR-PL) and photocurrent (PC) measurements reveal the relaxation dynamics of the nonequilibrium carriers from the Si host to the Er 3+ precipitates.…”