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Room-temperature photoluminescence lifetime for the near-band-edge emission of (000 1 ˉ ) p-type GaN fabricated by sequential ion-implantation of Mg and H
摘要： Photoluminescence (PL) spectra of (000(cid:2)1) N-polar p-type GaN fabricated by using the sequential ion-implantation of Mg and H with subsequent high temperature annealing exhibited the near-band-edge (NBE) emission at 300 K. The longest PL lifetime (sPL) for the NBE emission of the sample with Mg and H concentrations of 1 (cid:2) 1019 and 2 (cid:2) 1020 cm(cid:3)3, respectively, annealed at 1230 (cid:4)C was 18 ps at 300 K. This value is almost comparable to that of the (0001) Ga-polar p-type Mg-doped GaN (p-GaN:Mg) homoepitaxial ?lm of the same Mg concentration. By correlating sPL and the concentration of major vacancy-type defects quanti?ed using positron annihilation spectroscopy, the electron capture-cross-section (rn) of the major nonradiative recombination centers (NRCs), namely, clusters of Ga vacancies (VGas) and N vacancies (VNs) such as (VGa)3(VN)3, is estimated at a few times 10(cid:3)13 cm2. This rn value is also comparable to that of the major NRCs in p-GaN:Mg epilayers, namely, VGa(VN)2 or VGa(VN)3, although the clustering sizes of the defects are different. These rn values are commonly larger than the hole capture-cross-section (rp ? 7 (cid:2) 10(cid:3)14 cm2) of the major NRCs, VGaVN divacancies, in n-type GaN.
关键词： p-type GaN,ion-implantation,Mg and H,electron capture-cross-section,photoluminescence,nonradiative recombination centers
更新于2025-09-23 15:21:21
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Highly luminescent and stable CH3NH3PbBr3 quantum dots with 91.7% photoluminescence quantum yield: Role of guanidinium bromide dopants
摘要： Although perovskite quantum dots (PQDs) have received considerable attention, defects in PQDs can significantly degrade the properties and device performance. In this study, we report on an effective strategy for synthesizing highly luminescent CH3NH3PbBr3 quantum dots (QDs) by a simple doping. To remove such defects, guanidinium bromide (GuBr) was doped into the CH3NH3PbBr3 QDs synthesized by the ligand-assisted reprecipitation technique. From XRD and TEM studies, the doping of GuBr into the QD lattices was verified. In addition, the surfaces of PQDs with and without GuBr dopants were analyzed by XPS to trace the metallic Pb acting as a major recombination center. The GuBr doping resulted in the size uniformity of QDs and effectively eliminated defects and metallic Pb, which enhanced the photoluminescence quantum yield (PLQY) through the inhibition of the non-radiative recombination pathway. Furthermore, the recombination dynamics in the QDs were examined by using time-resolved photoluminescence and fluorescence lifetime imaging to verify the role of GuBr dopants. By optimizing the amount of GuBr doping, the CH3NH3PbBr3 QDs with strong green emission achieved a maximum PLQY of 91.7%.
关键词： Photoluminescence quantum yield,Fluorescence lifetime imaging,CH3NH3PbBr3 quantum dots,Guanidinium bromide,Recombination centers
更新于2025-09-23 15:19:57