November 28, 2011 -- AKHAN Technologies has developed a shallow n-type diamond material over silicon that has characteristics such as a shallow ionization energy (250meV), high carrier mobility (>1000cm2/Vs in nanocrystalline diamond thin films), and no graphitic phases. The latter is important because graphitic films translate to low mobility (because of scattering sites). The material also provides for a 900A/mm2 current density at +2V forward bias in low voltage high current diode device applications.
In a detailed discussion about the technology in a podcast interview with ElectroIQ.com (below), Adam Khan, president of AKHAN Technologies, said that the bottleneck in development of diamond films has always been the fabrication of n-type diamond, “Because all previous demonstrations have featured either deep-level dopants where the ionization energy is at or greater than ~500meV, or have graphitic defects with ultralow mobility,” said Khan. “The announcement of this new shallow n-type diamond with ionization of around 250meV translates to a higher concentration of electrons that can contribute to conduction at room temperature.”
According to the company, microchips fabricated from its Miraj Diamond (see the figure) platform can run electronics at higher speeds (1841cm2/Vs versus <1400cm2/Vs for electron mobility and 1000cm2/Vs versus <450cm2/Vs for hole mobility), with increased power handling capability (75W/mm demonstrated [DC] in low field), without overheating (600ºC versus 150ºC maximum operating junction temperature). The company says that its new film has benefits (e.g., reduced losses, increased efficiency, reduced size and volume) for devices used in thinner/cheaper computers, longer lasting cell phone batteries, TV screens, among others.
|Figure 1a) A fully processed Miraj diamond wafer; b) Close-up view. SOURCE: AKAHN Technologies.|
The company has been working on its process libraries for the last 7 years – resolving issues such as cost, ease of processing, scalability, and integration. It has also been in discussions with several large consortia. “We’ve secured everything around this material required to commercialize it for microchip use and now we’re ready to show the global industry how it can make use of it today, and not five years from now, explained Khan. The company has been able to demonstrate use of its diamond films in UVLEDs, as well as in power and RF devices. “This use allows a high power element like an LED, to be integrated onto the same material as its power element, dramatically increasing its efficiency.”
No special or advanced industry tooling is required and the process is not restricted to any single diamond grain size or type (CVD polycrystalline, nanocrystalline, single crystal, etc.). With commercially available diamond films from both domestic and international sources, the processed material cost of diamond becomes cheaper than processed silicon where nearly 17,000 times less material is required by volume as compared to silicon for identical device functionality, according to the company.