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“We don’t need to prepare the sample on any special substrate or vacuum environment, and the measurement won’t perturb the sample during the imaging process. This advantage allows for in-situ measurements under many practical conditions. Furthermore, our imaging technique is an ultrafast measurement that can provide critical dynamic information, and its instrumentation is far less complicated and less expensive compared with scanning tunnelling microscopy and transmission electron microscopy.”


Rubicon revenues boosted


but losses increase Idle plant and development costs at the firm’s wafering facilities were the main cause of its negative margins


Rubicon Technology, Inc,. a provider of sapphire substrates and products to the LED, semiconductor, and optical industries, has reported financial results for its first quarter ended March 31st, 2014.


The company reported first quarter revenue of $14.3 million as compared with $11.5 million in the prior quarter.


(A) Optical image of a large area of monolayer MoS2 and (B) an SHG image of the same area revealing grains and grain boundaries where translational symmetry is broken to form 1D edge states


For the SHG imaging of molybdenum disulphide, Zhang and his collaborators illuminated sample membranes that are only three atoms thick with ultrafast pulses of infrared light.


The nonlinear optical properties of the samples yielded a strong SHG response in the form of visible light that is both tuneable and coherent. The resulting SHG-generated images enabled the researchers to detect “structural discontinuities” or edges along the 2D crystals only a few atoms wide where the translational symmetry of the crystal was broken.


“By analysing the polarised components of the SHG signals, we were able to map the crystal orientation of the molybdenum disulphide atomic membrane,” says Ziliang Ye, the co-lead author of the paper and current member of Zhang’s research group. “This allowed us to capture a complete map of the crystal grain structures, colour-coded according to crystal orientation. We now have a real-time, non- invasive tool that allows us explore the structural, optical, and electronic properties of 2D atomic layers of transition metal dichalcogenides over a large area.”


This work is described in detail in the paper, “Edge Nonlinear Optics on a MoS2 Atomic Monolayer,” by Xiaobo Yin et al in Science, Vol. 344 no. 6183 pp. 488-490, (2 May 2014). DOI: 10.1126/science.1250564


This research was supported by the DOE Office of Science through the Energy Frontier Research Centre program, and by the U.S. Air Force Office of Scientific Research Multidisciplinary University Research Initiative.


The general lighting segment of the LED market continued to strengthen in the first quarter as adoption of this disruptive technology continues to gain momentum.


Overall LED growth in the quarter was tempered by seasonality associated with the backlighting market. Demand from this market is typically lower at the beginning of the year. As a result, overall demand in the first quarter was similar to the prior quarter and sapphire pricing, therefore, remained fairly consistent with the previous quarter.


Rubicon reported progress in growing the wafer side of its business. It received its first production order for its recently introduced patterned sapphire substrates which will be delivered in the second quarter. The firm also received its first production order of four-inch polished wafers which started in the latter part of the first quarter.


Raja Parvez, President and CEO of Rubicon, commented, “Patterned sapphire substrates (PSS) and polished wafers are an important part of our strategy and I am pleased with the sales progress we made in the quarter.”


However, costs in the wafering operations were high in the quarter resulting in an increase in pre-tax loss from $9.1 million in the fourth quarter to $10.9 million in the first quarter.


Wafer costs were higher than normal due to the large number of PSS samples produced and the cost of establishing a four- inch polishing line


Furthermore, due to the increased number of wafers in June 2014 www.compoundsemiconductor.net 77


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