news digest ♦ Solar
gas emissions,” said Jack Curtis, First Solar Vice President, Sales and Business Development. “We believe that this project and others like it in Thailand will greatly benefit from our low-cost, environmentally leading technology, which has the smallest carbon footprint of any current PV technology.”
“We are delighted to have partnered with the Sonnedix Group on this project in Thailand and to be working with Thai authorities as they increasingly adopt utility-scale PV solar as a clean, affordable source of renewable energy,” said Kevin Berkemeyer, First Solar Senior Manager, Business Development. “We look forward to helping Thailand meet its energy needs and enhancing its energy security.”
Covering around 20 hectares, the Nakhon Ratchasima Solar Farm can supply enough electricity to meet the annual needs of about 5,100 average Thai homes. It is expected to generate more than 10,500 MW hours of clean, green electricity per year, offsetting carbon dioxide emissions of more than 6,500 tons a year. A Buddhist inauguration ceremony took place at the power plant last week.
The modules in the project are covered by First Solar’s prefunded module and recycling program.
Twisting the growth of III-V nanowires
MIT researchers say they can control the composition and structure of tiny indium nitride and indium gallium nitride wires as they grow
Nanowires, microscopic fibres that can be grown in the lab are a hot research topic, with a variety of potential applications including LEDs and sensors.
Now, a team of MIT researchers has found a way of precisely controlling the width and composition of these tiny strands as they grow, making it possible to grow complex structures that are optimised for specific applications.
Nanowires have been of great interest because 114
www.compoundsemiconductor.net March 2012
Nanowires fabricated using the new techniques developed by Silvija Gradečak and her team can have varying widths, profiles and composition along their lengths, as illustrated here, where different colours are used to indicate compositional variations (Image courtesy of the Gradečak laboratory)
Nanowires are grown by using “seed” particles, metal nanoparticles that determine the size and composition of the nanowire. By adjusting the amount of gases used in growing the nanowires, Gradečak and her team were able to control the size and composition of the seed particles and the nanowires as they grew. “We’re able to control both of these properties simultaneously,” she says.
While the researchers carried out their nanowire- growth experiments with InN and InGaN, they say the same technique could be applied to a variety of different materials.
structures with such tiny dimensions, typically just a few tens of nanometres in diameter, can have very different properties than the same materials have in bulk.
That’s partly because on such a minuscule scale, quantum confinement effects come in to play. The behaviour of electrons and phonons within the material contribute a considerable amount to its properties. This can affect how it conducts electricity and heat or interacts with light.
What’s more, because nanowires have a significantly large amount of surface area in relation to their volume, they are particularly well-suited for use as sensors, points out Silvija Gradečak,who heads the research team at MIT.
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