We demonstrate triggered single photon emission at room temperature from a site-controlled III-nitride quantum dot embedded in a nanowire. Moreover, we reveal a remarkable temperature insensitivity ...of the single photon statistics, and a g (2)0 value at 300 K of just 0.13. The combination of using high-quality, small, site-controlled quantum dots with a wide-bandgap material system is crucial for providing both sufficient exciton confinement and an emission spectrum with minimal contamination in order to enable room temperature operation. Arrays of such single photon emitters will be useful for room-temperature quantum information processing applications such as on-chip quantum communication.
We report the selective-area growth (SAG) of Ga-polar thin GaN nanowires on patterned GaN/sapphire (0001) substrates using metalorganic chemical vapor deposition (MOCVD) with a continuous gas supply. ...It has been found that the anisotropy in the growth rates of the (0001) and the {1–100} facets of GaN reaches a maximum at low precursor flow rates for both Ga source and NH3. It has also been revealed that the SAG efficiency which is dependent on pattern fill-factor should be properly taken into account in order to grow thin GaN nanowires. Based on these findings, we demonstrate the growth of GaN nanowires with a diameter of 50nm, which is the smallest reported so far by selective-area MOCVD. Optical properties of a single GaN nanowire have been investigated by low temperature micro-photoluminescence. It has been shown that an appropriate shell layer is effective to considerably improve the properties, suggesting the importance of controlling surface states.
► Selective-area growth of GaN nanowires was demonstrated by continuous-flow MOCVD. ► The anisotropy in the growth rates reaches a maximum at low precursor flow rates. ► The selective area growth efficiency is dependent on pattern fill-factor. ► Surface states can be reduced by introducing an appropriate shell layer.
Sources of single photons are of central importance for the realization of several quantum information technologies including teleportation, cryptography, true random number generation, metrology, ...and some varieties of quantum computing. In principle the generation of single photons can be achieved via an optical transition in a quantum two-level system sufficiently separated from its environment. Solid-state semiconductor quantum dots are convenient structures that can provide such two-level systems, with engineered and tunable transition energies, but cryogenic temperatures are required in the vast majority of experiments in order to facilitate both carrier confinement and spectral isolation. The large-scale on-chip integration of such devices, however, due to inherent system heating, will require individual elements that can operate at temperatures in excess of room temperature. Here we report single-photon emission from an isolated state in a position-controlled GaN nanowire quantum dot at an unprecedented ambient temperature of 350 K (170 °F, 77 °C).
We report the metalorganic chemical vapor deposition growth of site-controlled single GaN quantum dots (QDs) in nanowires. The structure design has been optimized to maximize the luminescence ...intensity. First we have investigated the effect of the growth template on the sapphire (0001) substrate. It is found that even when the nanowire growth is performed on high defect density AlN, no degradation of the QD emission is observed (when compared to those dots grown on thick, higher quality GaN templates). As a consequence, the signal-to-noise ratio of the GaN QD emission could be improved by using the AlN templates, which exhibit a less intense background emission. Additionally, we have investigated the effect of the surface morphology of the underlying Al(Ga)N shell layers on the optical properties of the structures. When employing an AlGaN shell with smooth surface morphology, sharp single luminescence peaks from the QDs are clearly observed at around 4.2eV.
► We demonstrated the site-controlled growth of single GaN quantum dots in GaN/AlGaN nanowires. ► We have investigated the effect of the growth template and the surface morphology of the shell layer. ► Excellent signal-to-noise ratio of QD emissions was obtained by using AlN templates. ► Sharp single luminescence peaks are clearly observed by employing a smooth AlGaN shell layer.
We report the detection of fully confined excited states and the zero-absorption region of individual site-controlled GaN/AlGaN nanowire quantum dots using photoluminescence excitation spectroscopy, ...which provides evidence of the true zero-dimensional discrete density of states of such quantum dots. Because of the strong quantum confinement in these dots, the p-shell, d-shell, and even higher energy (including some f-shell) states of a single quantum dot are observed, which provides unprecedented insight into the electronic structure. Several emitters are measured and used to build up an average picture of the electronic structure of a single quantum dot via comparison to theoretical simulations.
에너지 저감을 위한 사용자 및 위치인식 기술 적용 디밍 조명제어 시스템 연구 최기현(Kihyun Choi); 김용성(Yongseong Kim); 이행우(Henagwoo Lee) ...
설비공학 논문집, 27(1),
2015, 2015-01, Letnik:
27, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Although research and technology developments have recently increased to save lighting energy within buildings, such research and technology development are judged to be unsuitable for energy savings ...since they are limited in the sense that the application of the technology is fragmented. This study proposes a user and location awareness technology applied to dimming lighting control system and verified the effectiveness of energy savings by building a test bed. The results were as follows : 1) This study suggested a user and location awareness technology applied to dimming lighting control system. 2) The system shows 96.6% and 82.8% energy saving rates, respectively, on the basis of one user, compared to an on/off lighting control and the user and location awareness technology applied to on/off lighting control system. 3) The energy consumption of the user and location awareness technology applied to on/off lighting control system and the user and location awareness technology applied to dimming lighting control system increased to 96.6%, 88.3%, and 59.6% and 82.8%, 85.0%, 51.5%, respectively, on the basis of one, two, and three users, compared to the on/off lighting control system. This study confirmed the energy saving performance of the user and location awareness technology applied to the dimming lighting control system through performance evaluation. In this regard, further study needs to be undertaken to evaluate the performance at night time.
In this article, we report the reliability characterization of 7-nm technology, in which the highly scaled sixth generation of FinFETs and 256-Mb static random access memory (SRAM) cells were newly ...developed by featuring extreme ultraviolet (EUV). The intrinsic reliability mechanisms of 7-nm FinFET including hot carrier injection (HCI), bias temperature instability (BTI), and time-dependent dielectric-breakdown (TDDB) are similar to that of the previous nodes, and would not be degraded by introducing the scaled FinFET. Moreover, we found that the use of EUV single patterning of middle of line (MOL) and back end of line (BEOL) improves reliability distribution remarkably as compared to the previous nodes using argon fluoride (ArF) multiple patterning techniques. We successfully demonstrated SRAM and logic high-temperature operating life (HTOL) up to 500 h, indicating the robustness of product-level reliability. These findings strongly suggest that the 7-nm technology featuring EUV is fully ready for high-volume manufacturing as well as providing a near future logic production with high-quality reliability.
Self-heating effect (SHE, \Delta T_{sh}) has been aggravated due to compact layout footprint in advanced FinFET technology, which needs a significant concern for device performance, variability and ...reliability co-optimization. In this paper, we characterize and model the FinFET SHE with technology scaling down as well as BEOL Joule-heating effect (JHE, \Delta {T}_{jh}), demonstrating the device with taller and narrower fin, shorter CPP presents higher \Delta {T}_{sh}, and there is a strong thermal coupling between BEOL metal layers, FEOL and BEOL. Therefore, accurate FEOL SHE and BEOL JHE should be considered for HCI, ON-state TDDB and EM reliability lifetime prediction.
Time dependent variability has become a significant concern for End-of-lifetime(EOL) reliability prediction for advanced technology with continuous scaling. In this work, we explore time dependent ...variability of BTI and HCI on our advanced FinFET technology to demonstrate that Defect-Centric model is a good candidate to describe both of them and there is no obvious difference between 8nm and 7nm for BTI and HCI variation η parameter. Thus, a framework is proposed for BTI and HCI EOL degradation prediction with given ppm criteria.
In this paper, we report middle-of-the-line (MOL) reliability characterization of recessed-diffusion-contacts adopted sub-5nm logic technology. The intrinsic MOL reliability including ...voltage-ramp-to-breakdown (Vramp) and time-dependent-dielectric-breakdown (TDDB) shows a notable improvement. MOL breakdown voltage (Vbd) is also comparable when a gate contact is placed next to a recessed-diffusion-contact. MOL Vramp related process parameters, such as critical dimension and height, are explained. MOL Vbd as an early diagnosis tool for process maturity, such as contact misalignment and dynamic voltage screening (DVS), on sub-5nm logic technology is addressed.
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