March 8, 2010 Australian Broadcasting Corporation
An international team of scientists has developed a new type of semiconductor that could lead to faster and more efficient computers with over double the average existing hard-drive storage capacity.
The new research centres on a class of semiconductor called magnetic quantum dots.
These crystals — so small they’re measured in billionths of a metre, or nanometres — were first developed about 15 years ago and are used in computer chips, solar cells, LEDs and diode lasers.
Semiconductors act as a switch, altering or moving the movement of electrons in a circuit. Quantum dots have the ability to also allow electrons to give off photons on command.
The new work, reported today in the journal Nature Materials, describes a class of quantum dots that not only control electrons, but also have good magnetic properties allowing them to read the electron’s spin.
The research team claims it’s the first successful synthesis of magnetic quantum dots above room temperature.
The researchers were also able to demonstrate electric field control using the quantum dots at temperatures up to 100 Kelvin, or –173 C.
Prof. Jin Zou, chair in nanoscience at the University of Queensland’s Centre for Microscopy and Microanalysis, said that by detecting electron spin, scientists can find new uses for quantum dots.
“Quantum dots with magnetic properties have multiple uses both optical and magnetic,” said Zou.
Zou said the key was getting just the right concentration of manganese mixed in with the germanium matrix of the quantum dot.
“Manganese has characteristics that in combination with other semiconductor atoms, allows magnetic properties to be achieved,” he said.
“But the amount must be small — just five per cent — so as not to lose the qualities you’re after,” said Zou.
2 years of research to reach goal
It has taken the team, which included researchers at the University of California, Los Angeles, and computer chip maker Intel, two years of research to achieve their goal.
Zou said the research could lead to advances in computer technology.
“The new technology could lead to faster and larger storage hard drives that use less power, as well as new ways of communications,” he said.
“It could also open up new frontiers like spintronics, a very hot topic internationally,” said Zou.
Spintronics, also called magnetoelectronics, is a relatively new technology that relies on a quantum property of electrons, called spin, that is closely related to magnetism. While electronics exploits only the charge of electrons, spintronics can use both their charge and spin.