Effects of intermixing on modulation p-doped quantum dot superluminescent light emitting diodes

Abstract

Different capping of quantum dot (QD) materials is known to produce different degrees of intermixing during a post-growth thermal annealing process. We report a study of the effect of different degrees of intermixing on modulation beryllium doped quantum dot superluminescent light emitting diodes (QD-SLEDs). The intermixed QD-SLEDs show high device performance whilst achieving a large central emission wavelength shift of approximately 100nm compared to the as-grown device. The evolution of the emission spectra and power with drive current suggest a transition from QD-like to QW-like behavior with increasing degree of intermixing. A selective area intermixed QD-SLED is demonstrated, and with optimized differential intermixing, such structures should allow ultra-broadband sources to be realized.

GaAs-Based Superluminescent Light-Emitting Diodes with 290-nm Emission Bandwidth by Using Hybrid Quantum Well/Quantum Dot Structures

“…Here, a resolution of 2.9 μm is obtained, indicating that a 0.4-μm penalty is introduced to the OCT system axial resolution due to the PSF side lobes (due to the non-Gaussian emission spectrum) of the device [2, 37]; this “penalty” may be reduced by reducing the spectral dips between QD GS and ES, and QD ES and QW. This can be achieved by chirping the QDs to have different emission wavelengths [38] or post-growth intermixing [39].

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InAs/GaAs quantum-dot intermixing: comparison of various dielectric encapsulants

“…A remarkable observation that is worth mentioning about this film is the broadened emission with equal intensities from both GS and ES transitions of QDs annealed at low temperature (650°C), indicating increased compositional fluctuation at the interface between the QD and the surrounding matrix as compared to TiO 2 and ZnO capping, leading to a dispersive QD potential profiles, in particular, affecting the smaller dots with higher intermixing rate as discussed earlier. 36 An ultrabroad PL linewidth of ∼165 nm from this single capped low-temperature intermixed SAQD structure, centered at ∼1140 nm is again highly attractive for biomedical imaging, in the lowcoherence interferometry system such as optical coherence tomography. 13,22 …”

QD Ultrafast and Continuous Wavelength Laser Diodes for Applications in Biology and Medicine

“…Here, a single InGaAs QW is introduced into a multilayer stack of QDs, spectrally positioned to compensate the losses induced by the higher ESs of the dots. As a result, the modal gain at room temperature is extended to 300 nm, covering wavelengths from 1.1 to 1.4 μm [102]. Finally, an alternative method is to laterally integrate different gain elements to vary the emission energy across one device, as seen in the schematic diagram ( Figure 5.21).…”

“…Finally, an alternative method is to laterally integrate different gain elements to vary the emission energy across one device, as seen in the schematic diagram ( Figure 5.21). This can be achieved by either selective area epitaxial growth [85] or by selective area intermixing [102]. Despite being promising, both these methods face the challenge of spatially varying the emission wavelength of the active gain material while maintaining its high quality.…”