Diamonds may fire up your computer

Diamonds when suitably doped, become excellent conductors of electricity but do not retain heat like other semiconductors

Nearly octahedral diamond crystal in matrix. Photo: Wikimedia Commons
Nearly octahedral diamond crystal in matrix. Photo: Wikimedia Commons

Researchers have begun increasingly experimenting with diamonds as a substitute for silicon chips or “doped diamonds” as semiconductors to be used as transistors in computers.

Diamond is the hardest material known besides being a good conductor of heat. When suitably doped, it becomes an excellent conductor of electricity but does not retain heat as other semiconductors like silicon do. Doping is a process of introducing impurities in an extremely pure semiconductor to make it a good conductor of electricity.

On 23 March, researchers at the Ohio State University revealed that diamond also transmits spin (one of two types of angular momentum, or rotational momentum, in quantum mechanics) better than most metals, lending it the so-called “spintronics” ability that may help manufacturers use diamonds to transmit data in computer circuits some day, making computers faster and more powerful.

A team led by Chris Hammel, Ohio eminent scholar in experimental physics at Ohio State, placed a tiny diamond wire in a magnetic resonance force microscope and detected that the spin states (from fast to slow) inside the wire varied according to a pattern.

“If this wire were part of a computer, it would transfer information. There’s no question that you’d be able to tell at the far end of the wire what the spin state of the original particle was at the beginning,” said Hammel in a press statement.

The findings, first reported in the 23 March issue of the journal Nature Nanotechnology, represent the first steps along a road that could one day lead to diamond transistors.

Normally, a diamond does not carry spin because its carbon atoms are locked together. So researchers had to seed the wire with nitrogen atoms to create unpaired electrons that could spin (the wire contained just one nitrogen atom for every three million diamond atoms).

The physicists also had to chill the wire to 4.2 Kelvin (about -452 degrees Fahrenheit or -269 degrees Celsius) to slow the spins so that they could be detected. However, it will be a while before anyone can do this experiment at room temperature, admitted Hammel.

And if you thought that the price tag for a diamond wire would be a major deterrent, Hammel said it cost a mere $100 since it was made of synthetic, rather than natural, diamond.

The concept of having a diamond chip or a diamond transistor firing up your computer has always excited researchers.

Transistors are electronic switches that control the flow of current from one part of a circuit to the next. They are typically made from semiconductors—materials that allow electric current to flow through them only under certain controlled conditions.

On 4 August, 2011, a team of electrical engineers at US-based Vanderbilt University developed all the basic components needed to create microelectronic devices out of thin films of nanodiamond—diamond versions of transistors and even logical gates that are a key element in computers.

Diamond-based devices have the potential to operate at higher speeds and require less power than silicon-based devices, research professor of electrical engineering Jimmy Davidson then said. Diamond is the most inert material known, he pointed out, so these devices are largely immune to radiation damage and can operate at much higher temperatures than those made from silicon.

These devices are so small that about one billion of them can be fabricated from a single carat of diamond. This means will not be very expensive to produce, thus making the cost of producing nanodiamond devices competitive with those of silicon.

On 5 April 2012, a team that included scientists from the University of Southern California (USC) built a quantum computer in a diamond, the first of its kind to include protection against “decoherence”—loss of observable information.

The team included USC professor Daniel Lidar and USC post-doctoral researcher Zhihui Wang.

The team’s diamond quantum computer system featured two quantum bits, or qubits, made of subatomic particles.

As opposed to traditional computer bits that encode distinctly either a one or a zero (a bit is the basic unit of information in computing, most commonly represented by values—0 and 1), qubits can encode a one and a zero at the same time. This property, called super-position, along with the ability of quantum states to “tunnel” through energy barriers, some day will allow quantum computers to perform optimization calculations much faster than traditional computers, the researchers said in a statement.

The team was able to demonstrate that its diamond-encased system did indeed operate in a quantum fashion by seeing how closely it matched “Grover’s algorithm”, which states that a quantum computer will be able to find a specified entry in an unsorted list on the first try, every time.

Lidar and Wang’s computer picked the correct choice on the first try about 95% of the time.

On 6 January, scientists at the Tokyo Institute of Technology developed a new transistor made from diamond. Mutsuko Hatano and co-workers at the Tokyo Institute of Technology succeeded in fabricating a new design of transistor using diamond doped with phosphorus and boron.

This was the first transistor of its kind to be made from diamond and to function accurately even at higher temperatures.

“The present work is still just the first step,” Hatano then said. The same holds true for a computer that will run on a diamond chip.

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