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Title: MAPbBr 3 First‐Order Distributed Feedback Laser with High Stability
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Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Advanced Photonics Research
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract

    2D photonic crystal (PhC) lasing from an InP nanowire array still attached to the InP substrate is demonstrated for the first time. The undoped wurtzite InP nanowire array is grown by selective area epitaxy and coated with a 10 nm thick Al2O3film to suppress atmospheric oxidation and band‐bending effects. The PhC array displays optically pumped lasing at room temperature at a pulsed threshold fluence of 14 µJ cm−2. At liquid nitrogen temperature, the array shows lasing under continuous wave excitation at a threshold intensity of 500 W cm−2. The output power of the single mode laser line reaches values of 470 µW. Rate equation calculations indicate a quality factor ofQ ≈ 1000. Investigations near threshold reveal that lasing starts from isolated islands within the pumped region before coherently merging into a single homogeneous area with increasing excitation power. This field emits a lasing mode with an average off‐normal angle of ≈6°. Single mode lasing with the nanoarray still attached to the InP substrate opens new design opportunities for electrically pumped PhC laser light sources.

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    GaAs‐AlGaAs based nanowire (NW) lasers hold great potential for on‐chip photonic applications, where lasing metrics have steadily improved over the years by optimizing resonator design and surface passivation methods. The factor that will ultimately limit the performance will depend on material properties, such as native‐ or impurity‐induced point defects and their impact on non‐radiative recombination. Here, the role of impurity‐induced point defects on the lasing performance of low‐threshold GaAs(Sb)‐AlGaAs NW‐lasers is evaluated, particularly by exploring Si‐dopants and their associated vacancy complexes. Si‐induced point defects and their self‐compensating nature are identified using correlated atom probe tomography, resonant Raman scattering, and photoluminescence experiments. Under pulsed optical excitation the lasing threshold is remarkably low (<10 µJ cm−2) and insensitive to impurity defects over a wide range of Si doping densities, while excess doping ([Si]>1019 cm−3) imposes increased threshold at low temperature. These characteristics coincide with increased Shockley‐Read‐Hall recombination, reflected by shorter carrier lifetimes, and reduced internal quantum efficiencies (IQE) . Remarkably, despite the lower IQE the presence of self‐compensating Si‐vacancy defects provides an improved temperature stability in lasing threshold with higher characteristic temperature and room‐temperature lasing. These findings highlight an overall large tolerance of lasing metrics to impurity defects in GaAs‐AlGaAs based NW‐lasers.

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    Electrically pumped lasing from hybrid organic–inorganic metal‐halide perovskite semiconductors could lead to nonepitaxial diode lasers that are tunable throughout the visible and near‐infrared spectrum; however, a viable laser diode architecture has not been demonstrated to date. Here, an important step toward this goal is achieved by demonstrating two distinct distributed feedback light‐emitting diode architectures that achieve low threshold, optically pumped lasing. Bottom‐ and top‐emitting perovskite light‐emitting diodes are fabricated on glass and Si substrates, respectively, using a polydimethylsiloxane stamp in the latter case to nanoimprint a second‐order distributed feedback grating directly into the methylammonium lead iodide active layer. The devices exhibit room temperature thresholds as low as ≈6 µJ cm−2, a peak external quantum efficiency of ≈0.1%, and a maximum current density of ≈2 A cm−2that is presently limited by degradation associated with excessive leakage current. In this low current regime, electrical injection does not adversely affect the optical pump threshold, leading to a projected threshold current density of ≈2 kA cm−2. Operation at low temperature can significantly decrease this threshold, but must overcome extrinsic carrier freeze‐out in the doped organic transport layers to maintain a reasonable drive voltage.

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