Kotura reportedly has over 120 granted or pending patents in CMOS photonics and packaging design, and successfully integrated multiple high speed active and passive optical functions onto a silicon chip. Mellanox says that the addition of Kotura’s technology will enable its interconnect products to reach 100Gb/s and beyond bandwidth, and have longer reach optical connectivity at a lower cost

Eyal Waldman, president, CEO and chairman of Mellanox Technologies stated, “We expect that the proposed acquisition of Kotura’s technology and the additional development team will better position us to produce 100Gb/s and faster interconnect solutions with higher-density optical connectivity at a lower cost. We welcome the great talent from Kotura and look forward to their contribution to Mellanox’s continued growth.”

The agreement includes an expanded licensing and manufacturing supply relationship. Bridgelux says it will continue to develop and market its GaN-on-Sapphire LED products as a fabless solid state lighting company. The companies began their collaboration in early 2012, and later in 2012 Toshiba became an investor in Bridgelux. As part of the previously announced agreement, Toshiba hired Bridgelux’s GaN-on-Silicon development team. In turn, Bridgelux reportedly retains a majority of its revenue generating operations as a fabless LED company.

“We are thrilled to be moving into the next stage of our joint work with Toshiba to advance GaN-on-Silicon-based solid state lighting technologies,” said Brad Bullington, CEO of Bridgelux. “As we outlined last month, Bridgelux will focus on commercializing, productizing and bringing to market GaN-on-Silicon technologies alongside a proven global scale semiconductor manufacturer. At the same time, we remain committed to our GaN-on-Sapphire business and look forward to continuing to provide world-class innovation and service to our customers.”

IQE says that GaN power amplifiers offer superior power capability, efficiency, bandwidth and linearity compared with silicon (Si) or gallium arsenide (GaAs)-based technologies commonly used. IQE contends that GaN power amplifiers also lower overall system costs. Additionally, the company says that GaN-based low-noise amplifiers exhibit improved robustness, noise figure and dynamic range when compared to incumbent solutions. According to IQE, GaN-based transistors can operate at high temperatures, thus reducing system cost, size and weight.

IQE says that the higher cost of epitaxial material grown on 100mm SiC substrates has limited the commercial market penetration of GaN HEMTs. However, IQE says that its 150mm products are compatible with LDMOS processing lines, and its customers have demonstrated the use of LDMOS to fabricate GaN HEMTs.

Russ Wagner, VP of IQE wireless business unit said,"Scaling up to 150mm wafer diameter is a critical milestone on the path to technological maturity and wide market acceptance of GaN HEMTs on SiC." Wagner added,"We are very pleased with the quality of substrates supplied by II-VI Inc. and look forward to continuing our partnership as we execute volume production ramp and expand IQE's range of advanced high-power high-frequency transistor products for defense and wireless infrastructure applications."

The researchers note that green-emitting nitride semiconductor LED structures tend to suffer from low light output due to the difficulty in producing the high-indium-content indium gallium nitride (InGaN) needed for longer-wavelength light emission. In addition to the material quality challenge, strain induced by the lattice mismatch with pure GaN leads to large piezoelectric effects, giving electric fields that tend to pull electrons and holes apart, reducing rates of recombination into photons (i.e. the quantum-confined Stark effect, or QCSE), thus reducing quantum efficiency.

The Chinese team inserted a layer of lower-indium-content InGaN before the high-In-content light-emitting layer. Simulations suggested that such a layer could reduce the strain-dependent electric fields in the active light-emitting multiple quantum well (MQW) structure.

MOCVD on C-plane sapphire was used to produce epitaxial material with a low-In-content InGaN shallow quantum well (SQW) step. A 325nm helium-cadmium laser was used to excite the photoluminescence spectra of the materials at low temperature (85K) and room temperature (298K). One effect of the SQW was to reduce the width of the spectral peak full-width at half maximum (FWHM) at 85K from 16.7nm for the conventional LED material to 13.1nm for the SQW material. The 298K measurement reduced the conventional FWHM of 20.1nm to 15.7nm. The peak intensity was also higher with the SQW structure, therefore the SQW material had improved crystal quality.

The peak height for the SQW material at 298K was 55.1% that at 85K. The corresponding ratio for the conventional structure was 24.1%. The higher ratio for the SQW material indicates a higher rate of radiative recombination and higher internal quantum efficiency (IQE).

The electroluminescence was measured in an integrating sphere, giving light output power–current–voltage (L–I–V) results. The voltage performance is similar in the SQW and conventional devices. However, the light output at 150mA is 28.9% greater in the SQW LED (49.3mW) over the conventional device (38.4mW).

The researchers point out that improved overlap of the electron and hole wavefunctions in the device leads to improved recombination into photons. The external quantum efficiency (EQE) increased from 10.2–13.3% over the conventional LED performance.

TriQuint demonstrated its new GaN-on-diamond, high electron mobility transistors (HEMT) in conjunction with partners at the University of Bristol, Group4 Labs and Lockheed Martin under the Defense Advanced Research Projects Agency’s (DARPA) Near Junction Thermal Transport (NJTT) program. TriQuint claims that its new technology enables RF amplifiers that are up to three times smaller or up to three times the power of today’s GaN solutions.

NJTT focuses on device thermal resistance 'near the junction' of the transistor. Thermal resistance inside device structures can be responsible for more than 50% of normal operational temperature increases. TriQuint research has shown that GaN RF devices can operate at a much higher power density and in smaller sizes, through its highly effective thermal management techniques. Operating temperature largely determines high performance semiconductor reliability. It’s especially critical for GaN devices that are capable of very high power densities.

James L. Klein, vice president and general manager for infrastructure and defense products commented, “By increasing the thermal conductivity and reducing device temperature, we are enabling new generations of GaN devices that may be much smaller than today’s products. ”

Company CTO Boris Epelbaum commented, "Further diameter increase in our patented tungsten based furnaces is not limited as we are using SiC as initial seed."

Wafer polishing drastically improved as well for the AlN substrates. "The corresponding wafers feature surface roughness of less than 0.3 nm and are highly UV transparent," said Octavian Filip, director of wafering.

Dr. Mark J. Furlong, VP IQE Infrared, stated, “The opportunity to establish a new business unit with an exclusive focus on infrared materials will give IQE better opportunities to combine its substrate and epitaxial wafer products for serving a broader range of customers and even broader range of infrared device applications."