By Charles Martinez 2008
Gallium nitride (GaN) is a semiconductor that possesses unique characteristics that make it advantageous for the creation of efficient optoelectronic devices in addition to high power and high temperature applications. These devices should find wide practical applications in commercial markets and also in defence. The Inspec Database covers many of these emerging technologies. Potential and current uses of nitride technology along with their relevant Inspec classification codes, are as follows:
1) GaN could be used potentially for large TV screens or smaller full colour panels in trains or buses. Full colour displays were not possible because blue and green LED’s were not bright enough. GaN based LED’s are much more efficient and therefore provide another possibility for blue and green LED’s.
|B4260D||Light emitting diodes|
2) LED’s consume less c and last longer therefore bolstering energy and cost saving. Nitride based semiconductors (emitting in the UV) can also be combined with phosphor converters in order to generate white light. This is unfortunately not yet possible due to the price factor in the manufacture of LED’s. Higher power output, even with higher efficiency, presents significant challenges to manage the heat generated by LED’s, since excess heat rapidly degrades the life of the LED.
This has warranted the development of alternative approaches to manufacture LED’s in order to offer reduction of LED power consumption, improved thermal management, and more cost-efficient and reliable LED lighting systems, enabling LED’s to realise their full potential.
|B4260D||Light emitting diodes|
3) Room temperature gallium nitride based lasers with impressive lifetimes have already been demonstrated. There is a significant market for optical reading and writing of data in CD, DVD and opto-magnetic memories.
|A4255P||Lasing action in semiconductors|
|B4210||Optical storage and retrieval|
4) Microwave amplifiers for wireless communications systems that translate into better reception on mobile phones and fewer low-earth satellites and transmitting stations in the environment. The greater transmitting power and higher efficiencies supplied by GaN materials means that fewer geostationary satellites will do the same job as many more low-earth satellites.
|B1350F||Solid-state microwave circuits and devices|
|B1350H||Microwave integrated circuits|
|B6250||Radio links and equipment|
5) Aerospace components that can operate over a wide temperature range and remain unaffected by radiation. Due to GaN’s chemical composition it is widely expected that the material will exhibit greater radiation hardness.
|B2550R||Radiation effects on semiconductor devices|
|B7600||Aerospace facilities and techniques|
Despite GaN’s viable technological applications, some of the basic material properties of the group III nitride materials are not fully understood. Whilst extrinsic effects mentioned above can be improved by better growth and fabrication methods, the basic properties cannot currently be controlled; therefore the role which they play in device operations must be further studied. Although transport measurements and optical characterisation have gone some way to understanding these issues, there are still areas that need investigation. Inspec classification covers the main nitride semiconductor research topics:
|A7220||Electrical conductivity phenomena in semiconductors and insulators|
|A7280E||Electrical conductivity of II-VI and III-V semiconductors|
|A7360L||Electrical properties of II-VI and III-V semiconductors (thin films/low dimensional structures)|
|A7830G||Infrared and Raman spectra in inorganic crystals|
|A7840G||Visible and ultraviolet spectra -of II-VI and III-V semiconductors|
|A7855E||Photoluminessence in II-VI and III-V semiconductors|
|A7865K||Optical properties of II-VI and III-V semiconductors (thin films/low dimensional structures)|
|B2520D||II-VI and III-V semiconductors|