Meladom Sandhya K, Arackal Sarath, Sreedharan Anjusree, Sagar Srikrishna, Das Bikas C
School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) Vithura Thiruvananthapuram 695551 India
RSC Adv. 2018 Jul 26;8(47):26771-26781. doi: 10.1039/c8ra03631d. eCollection 2018 Jul 24.
A robust doping strategy of Mn ions in CdSe QDs has been developed in aqueous medium with mild microwave irradiation using the short-chain capping ligand 3-MPA. The concentration of the dopant is varied stoichiometrically in order to measure its effect on the conductivity of QD solids for further potential applications in the future. The synthesis parameters of CdSe QDs have been optimized to produce a uniform size among various samples to decouple the doping dependent conductivity from their bandgap. Doping yield is measured extensively by several studies like EDS, ICP-AES, and XPS. The layer-by-layer electrostatic assembly method has been exploited to fabricate thin film devices. - characteristics reveal that the electrical conductivity of 2% Mn-doped CdSe QD devices is enhanced on the order of ∼10 compared to its undoped counterpart. The "auto-ionization" of Mn dopants in CdSe QDs due to the quantum confinement effect is one reason for this jump in conductivity as described in the Poole-Frenkel effect. STM measurements of the monolayer QD device shows its resistive switching properties. Importantly, the threshold voltage of switching decreased with the increase of doping concentration. All these results confirm the efficiency of Mn doping in zinc-blende CdSe QDs in aqueous medium, by avoiding the "self-purification" effect of CdSe QDs, and their further application as a potential candidate for future memristor devices.
在水相中，利用短链封端配体3 - MPA，通过温和的微波辐射，开发了一种在CdSe量子点中稳健的锰离子掺杂策略。为了测量其对量子点固体电导率的影响，以便未来进一步潜在应用，按化学计量改变掺杂剂的浓度。优化了CdSe量子点的合成参数，以在各种样品中产生均匀的尺寸，从而将掺杂依赖的电导率与其带隙解耦。通过能谱仪（EDS）、电感耦合等离子体原子发射光谱法（ICP - AES）和X射线光电子能谱（XPS）等多项研究广泛测量掺杂产率。利用逐层静电组装方法制造薄膜器件。特性表明，与未掺杂的对应物相比，2%锰掺杂的CdSe量子点器件的电导率提高了约10倍。如普尔 - 弗伦克尔效应所述，由于量子限制效应，CdSe量子点中锰掺杂剂的“自电离”是电导率跃升的一个原因。单层量子点器件的扫描隧道显微镜（STM）测量显示出其电阻开关特性。重要的是，开关的阈值电压随着掺杂浓度的增加而降低。所有这些结果证实了在水相中闪锌矿型CdSe量子点中锰掺杂的效率，通过避免CdSe量子点的“自净化”效应，以及它们作为未来忆阻器器件潜在候选者的进一步应用。
