The GaN LED on silicon does not have to be affected by stress, and a certain amount of stress hinders the output power. A British research team used in-situ tools to monitor temperature and wafer curvature to produce flat 150mm epitaxial wafers with low dislocation density and mount the chips into the device, resulting in an internal quantum efficiency approaching 40%.
The US Energy Agency believes that the widespread use of LED lighting will place demands on lower cost, more efficient commercial devices. These two standards are recorded in the LED roadmap. For example, by 2015, LED lamps have a luminous efficiency of 150 lm/W and cost less than $5/thousand lumens.
The cost of LED lighting today is more than double that of this goal, and the cost of the chip alone accounts for about half of the cost. However, by shifting the production process to larger, lower cost substrates, the cost of processing is controlled, and the cost of the chip is therefore reduced by an order of magnitude.
Our UK Research Alliance is led by RFMD UK and the rest are from Cambridge University, Aixtron UK, QinetiQ and Forge Europa. With the UK Government Fund launched in April 2007, we received $450 in funding to achieve this goal. . Our research efforts are focused on developing high quality LEDs on a 150mm silicon platform. RFMD has now produced devices with nearly 40% internal quantum efficiency (IQE).
The entire work has a specific allocation. The University of Cambridge is responsible for the development of high-quality device materials in the first stage; QinetiQ provides growth and process support, and utilizes a wealth of semiconductor expertise to ensure efficient material development; it is then expanded by LED manufacturer RFMD; When the device manufacturer starts, the market work is handed over to LED application specialist Forge Europa.
The silicon substrate maintains stability at a typical growth temperature and is low in cost; its diameter can be increased to 300 mm, and the silicon surface is suitable for epitaxial growth. In combination with the above characteristics, the silicon substrate is selected as a platform for growing nitride. Silicon nitride epitaxial wafers can also be used in standard manufacturing equipment in the silicon industry, making chip production more cost effective, and the chip can be bonded and converted into packaged LEDs.
![Development of GaN LEDs on 150mm silicon wafers with MOVCD devices]()
A project led by UK government-funded, leading companies and research institutes to develop silicon-on-silicon GaN LEDs on 150mm silicon (111) substrates using MOCVD equipment, including RFMD UK team, Cambridge University, Aixtron UK, QinetiQ and Forge Europa .
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