backlink free directory. site rank

TrustDIR.org » Trusted SEO Web Directory » Ethical SEO » Better Traffic » Higher Sales

 

 

 

Top Hits       Articles & Tutorials       WEB SEO Directory Statistics       Latest Websites       Suggest Article  

Article Home » Business » Electronics



Nitride Cells Start Delivering High Efficiencies

Submitted on: Thu, 23 Jun 2011 06:16:54Views: 558
Engineers at Meijo University and Nagoya University have shown that InGaN/GaN superlattice structures can realize an external quantum efficiency (EQE) of more than 40 percent over the 380-425 nm range. And researchers at UCSB and the Ecole Polytechnique, France, have reported a peak EQE of 72 percent at 380 nm. Both cells have the potential to be incorporated into a traditional multi-junction device to harvest the high-energy region of the solar spectrum.

â??However, the ultimate approach is that of a single nitride-based cell, due to the coverage of the entire solar spectrum by the direct bandgap of InGaN,â?? says UCSBâ??s Elison Matioli.

He explains that the main challenge to realizing such devices is the growth of highquality InGaN layers with high indium content. â??Should this problem be solved, a single nitride solar cell makes perfect sense.â??

Matioli and his co-workers have built devices with highly doped n-type and p-type GaN regions that help to screen polarizationrelated charges at hetero-interfaces that limit conversion efficiency. Another novel feature of their cells are a roughened surface that couples more radiation into the device. Photovoltaics were produced by depositing GaN/InGaN p-i-n structures on sapphire by MOCVD. These devices featured a 60 nmthick active layer made of InGaN and a p-type GaN cap with a surface roughness that could be adjusted by altering the growth temperature of this layer .

The researchers measured the absorption and EQE of the cells at 350-450 nm (see Figure 2 for an example). This pair of measurements revealed that radiation below 365 nm, which is absorbed by GaN, does not contribute to current generation â?? instead, the carriers recombine in p-type GaN.

Between 370 nm and 410 nm the absorption curve closely follows the plot of EQE, indicating that nearly all the absorbed photons in this spectral range are converted into electrons and holes. These carriers are efficiently separated and contribute to power generation. Above 410 nm, absorption by InGaN is very weak. Matioli and his colleagues have tried to optimise the roughness of their cells so that they absorb more light. However, even with their best efforts, at least one-fifth of the incoming light is either reflected off the top surface or passes directly through the cell. Two options for addressing these shortcomings are to introduce anti-reflecting and highly reflecting coatings in the top and bottom surfaces, or to trap the incoming radiation with photonic crystal structures.

â??I have been working with photonic crystals for the past years,â?? says Matioli, â??and I am investigating the use of photonic crystals to nitride solar cells.â?? Meanwhile, Japanese researchers have been fabricating devices with higher indium content layers by turning to superlattice architectures. Initially, the engineers fabricated two type of device: a 50 pair superlattice with alternating 3 nm-thick layers of Ga0.83In0.17N and GaN, sandwiched between a 2.5 µm-thick n-doped buffer layer on a GaN substrate and a 100 nm p-type cap; and a 50 pair superlattice with alternating layers of 3 nm thick Ga0.83In0.17N and 0.6 nm-thick GaN, deposited on the same substrate and buffer as the first design and featuring an identical cap.

The second structure, which has thinner GaN layers in the superlattice, produced a peak EQE in excess of 46 percent, 15 times that of the other structure. However, in the more efficient structure the density of pits is far higher, which could account for the halving of the open-circuit voltage.

To realize high-quality material with high efficiency, the researchers turned to a third structure that combined 50 pairs of 3 nmthick layers of Ga0.83In0.17N and GaN with 10 pairs of 3 nm thick Ga0.83In0.17N and 0.6 nmthick GaN. Pit density plummeted to below 106 cm-2 and peak EQE hit 59 percent.

The team is aiming to now build structures with higher indium content. â??We will also fabricate solar cells on other crystal planes and on a silicon substrate,â?? says Kuwahara.

For more information on Indium Nitride , Semiconducting Devices

» Latest news on : Electronics
» Google News for: Nitride Cells Start Delivering High Efficiencies

Lates tweets about Business / Electronics

From @InseadSky on Fri Apr 16 10:38:26 EDT 2021
How does #IIoT and #AI pave the way to more productivity in the manufacturing industry? Find out in our #webinar 💻… https://t.co/cNvE07SWi0
From @InseadSky on Fri Apr 16 10:38:06 EDT 2021
Take a virtual tour through our #Electronics Works Amberg – where #SIMATIC produces SIMATIC – and gain insights int… https://t.co/zBAY3bk5Y9
From @tweetVala on Fri Apr 16 10:37:57 EDT 2021
@academy_share Pulz Electronics - Found the financials to be doing fine, but the chart looks in bad shape | possibl… https://t.co/kSjNi5yRCG
From @JoshuaScribner3 on Fri Apr 16 10:37:46 EDT 2021
RT @metpoliceuk: Officers in #Southall have seized an estimated £2.5m worth of fake designer clothes and electronics 👗📱 TSG officers opene…
From @aygoldvisualar1 on Fri Apr 16 10:37:31 EDT 2021
@Joiiiie_ As a gift; Food get eaten, Clothes fade and tear, Electronics get broken, Gadgets get outdated, But port… https://t.co/JQm9MdrVHD
From @Techedusolution on Fri Apr 16 10:37:30 EDT 2021
PRODUCT OF THE DAY: UniTrain System Following up with our lab of the week, the UniTrain is a multimedia e-learning… https://t.co/ImNqdevrsB
From @Je6Whx on Fri Apr 16 10:37:27 EDT 2021
RT @HexabitzInc: Subscribe to the #Hexabitz @YouTube #Channel !🎥🤓🌟💡https://t.co/PW4SqX23Bx #videobitz #technology #coding #makers #Linux #w…
From @InseadSky on Fri Apr 16 10:37:24 EDT 2021
Only [x] days left until our #webinar through #Electronics Works Amberg ( – where #SIMATIC produced SIMATIC). Regis… https://t.co/ao0tL5T2Gt
From @sprint_code on Fri Apr 16 10:37:21 EDT 2021
RT @HexabitzInc: Subscribe to the #Hexabitz @YouTube #Channel !🎥🤓🌟💡https://t.co/PW4SqX23Bx #videobitz #technology #coding #makers #Linux #w…
From @BuanaFrank3 on Fri Apr 16 10:37:07 EDT 2021
RT @BenjaminP3ters: unmanned artificial intelligence (AI) funding - Military & Aerospace Electronics Read more here: https://t.co/4DuAzWRw…
Copyright © 2008 - 2011     VIC Consulting - WEB Development, website promotion & SEO services
Autos neuves et usagées | Ottawa used cars, furniture & real estate | Toronto Business Electronics
Follow webseodirectory on Twitter