LEDs with a vertical geometry are promising candidates for deployment in solid-state lighting products because they can handle the high drive currents needed to deliver a high luminous output. Manufacturing this form of LED requires a wafer-to-wafer bonding process,which involves many variables that need to be optimised for the specific device design, say Thomas Uhrmann, Eric Pabo,Viorel Dragoi and Thorsten Matthias from EV Group.
A hike in LED manufacturing yields can ensure profitable production of lower cost chips and spur the growth of solid-state lighting. One way for fabs to produce more die that are in-spec is to introduce inspection tools for various steps of the process, alongside software that collates all the data and pin points process issues, says KLA-Tencor’s Director of Product Marketing, John Robinson.
Following years of quiet development, Solar Junction has recently shot to fame with recordbreaking triple-junction cells incorporating dilute nitrides. The next phase for the company is to ramp its manufacturing capacity and help CPV to carve out its own segment in the PV market. Richard Stevenson catches up with the plans of the Stanford start-up.
An internationally diverse,well-attended exhibition at euroLED showcased the tremendous growth of LED lighting products for general illumination. Although these solid-state sources account for only a tiny fraction of total lighting sales,many conference speakers argued that far greater market penetration will follow once these products are far cheaper and deliver better colour quality. Richard Stevenson reports.
In general, it has been a fairly good year for compound semiconductor shares, with many firms experiencing double-digit increases in value. But variations in market performance are huge: Fibre laser manufacturer IPG Photonics has more than tripled its share price in the last year, while LED chipmaker Cree has seen its share price plummet by nearly 50 percent. Richard Stevenson reports.
By the end of this decade SiC device sales will be netting a billion dollars and substrate revenues will be worth $350 million, according to market analyst Philippe Roussel from Yole Développement. He talks to Richard Stevenson about the chipmakers set to make the biggest splash and the type of substrate that they will be using.
Most of the LEDs that are made in China fall into one of two camps: either low performance, incredibly cheap emitters that backlight keypads and illuminate the likes of toys, children’s shoes and power indicators; or high-end power chips for general lighting that are fabricated through joint ventures with foreign LED manufacturers. Domestic chip production is ramping in both these sectors, contributing to overcapacity in the global market and driving down prices, reports Richard Stevenson.
Today’s switch-mode power converters restrict the efficiency of solar systems and hybrid electric vehicles. One way to lift this barrier, while cutting the bill of materials at the system level, is to replace the silicon transistors with SiC bipolar equivalents that can deliver currents of up to 50A, argues Fairchild’s Anders Lindgren.
The solar cell veteran found that the combination of a top cell of gallium indium phosphide and a bottom cell of gallium arsenide in the photvoltaic concentrator cell, were chemically compatible as they have the same lattice constant. His multi-junction cells have been used for space craft and terrestrial uses.
Widely used temperature-accelerated tests can overestimate the lifetime of GaN HEMTs. That’s because they fail to account for device failure mechanisms below the critical voltage that degrade the gate and lead to a surge in leakage current, says imec’s Denis Marcon, Thomas Kauerauf and Stefaan Decoutere.
Reducing packaged LED die costs to the new more aggressive roadmap target of $2.20/klm within five years will take some major innovations in manufacturing technology. The good news is that the manufacturing supply chain is making some major progress.
Are you are looking for a resource covering all aspects of III-Vs on silicon development, from growth approaches and in-situ monitoring tools to a survey of the capabilities of LEDs, lasers, transistors and solar cells? If so, you might consider investing in a copy of III-V Compound Semiconductors: Integration with Silicon based Micoelectronics, writes Richard Stevenson.