Received ZZZ, revised ZZZ, accepted ZZZ Published online ZZZ (Dates will be provided by the publisher.)Keywords (quantum dot, single photon, g (2) (0), photon extraction efficiency) We introduce novel metal-embedded semiconductor pillar structure including quantum dots as highly efficient single-photon sources for quantum information applications. We have developed related processes for fabricating the proposed structure, and have demonstrated strongly suppressed multi-photon generation and improved photon extraction efficiency. As a result, under non-resonant excitation, which is highly preferable for the practical use, single-photon purity with g (2) (0) as low as 0.015 has been measured. Extremely small semiconductor volume in the metal embedded structure is a crucial factor for this observation. Moreover, single-photon generation rate from a single quantum dot up to 6.4 million per second has been achieved.Copyright line will be provided by the publisher IntroductionFor quantum information applications, realization of efficient single-photon sources is one of the key issues. Semiconductor quantum dots (QDs) are a good candidate for realizing single-photon sources, entangled-photon-pair sources [1][2][3], and quantum gates [4] etc. Especially, in view of the single-photon sources based on QDs, high-bitrate on-demand generation is expected.However, for the practical use, two main issues are remaining. First, multi-photon generation evaluated by a second-order photon correlation function at zero time delay g (2) (0) should be minimized. For long-distance quantum key distribution, lower g (2) (0) is crucial for practical applications with high bit rate operation [5]. So far, many groups have reported single photon emission from QDs [6][7][8][9], and relatively low g (2) (0) values of 0.02-0.03 were reported in ref. 6, 7. However, these values have been obtained under p-shell resonant excitation which requires strict energy tuning. For practical devices driven by electrical pumping, further suppression of multi-photon generation without strict energy tuning is much preferable. Another issue is to approach the on-demand operation. Generally, photon extraction efficiency from QDs is less than 1% in the case of a planar surface due to large difference

A 70 mm x 80 mm OLED lighting panel with efficacy of 78.6 lm/W at 1000 cd/m has been demonstrated. We improved the efficacy of the panel by decreasing driving voltage. We adopted two approaches: optimize device structure by using high-mobility electron transport layers and improve luminous uniformity by embedding metal bus lines. 2

In this work, a thermal treatment technique under NH3 ambient for the recess surface of GaN‐MOSFETs is developed. Immediately following the fabrication process of the recess, the bottoms of these structures have rough surfaces and step‐terrace structures cannot be observed because of the plasma‐induced damage. However, clear step‐terrace structures are formed by the thermal treatment, and the RMS values of the surface roughness decrease from 0.26 to 0.14 nm, which is comparable to those of the as‐grown epitaxial film. In addition, it is confirmed that concentrations of impurity atoms introduced during the recess fabrication process are decreased by the thermal treatment. The channel mobility of the GaN‐MOSFETs without the thermal treatment is 118 cm2 Vs−1, whereas that of the device whose fabrication process includes the thermal treatment increased to 149 cm2 Vs−1. These results indicate that the thermal treatment under NH3 ambient is effective for reducing on‐state resistance of GaN‐MOSFETs.

No abstract

We have demonstrated the suppression of short-channel effects (SCEs) in normally-off GaN metal-oxide-semiconductor field-effect transistors (MOSFETs) with deep recessed-gate structures. TCAD simulation results show that the electric field concentration is effectively reduced at the recessed edge of MOSFETs with deeper recessed-gate structures. To demonstrate suppression of SCEs, MOSFET gate structures with recess depths ranging from 45 to 165 nm were fabricated and evaluated. Experimental results show that deeper recessed-gate structures are highly effective for suppressing drain-induced barrier lowering and improving subthreshold swing and threshold voltage roll-off.