Progress to fully optical computing and faster hybrid computing

New research has demonstrated how glass can be manipulated to create a material that will allow computers to transfer information using light. This development could significantly increase computer processing speeds and power in the future.

The challenge was to find a single material that can effectively use and control light to carry information around a computer. Much like how the web uses light to deliver information, we want to use light to both deliver and process computer data.

“This has eluded researchers for decades, but now we have now shown how a widely used glass can be manipulated to conduct negative electrons, as well as positive charges, creating what are known as ‘pn-junction’ devices. This should enable the material to act as a light source, a light guide and a light detector – something that can carry and interpret optical information. In doing so, this could transform the computers of tomorrow, allowing them to effectively process information at much faster speeds.”

The researchers expect that the results of this research will be integrated into computers within ten years. In the short term, the glass is already being developed and used in next-generation computer memory technology known as CRAM, which may ultimately be integrated with the advances reported.

CRAM is a kind of phase change memory Phase-change memory (also known as PCM, PCME, PRAM, PCRAM, Ovonic Unified Memory, Chalcogenide RAM and C-RAM) is a type of non-volatile random-access memory. PRAMs exploit the unique behaviour of chalcogenide glass. In the older generation of PCM heat produced by the passage of an electric current through a heating element generally made of TiN would be used to either quickly heat and quench the glass, making it amorphous, or to hold it in its crystallization temperature range for some time, thereby switching it to a crystalline state.

Nature Communication – n-type chalcogenides by ion implantation

The research by the University of Surrey, in collaboration with the University of Cambridge and the University of Southampton, has found it is possible to change the electronic properties of amorphous chalcogenides, a glass material integral to data technologies such as CDs and DVDs. By using a technique called ion doping, the team of researchers have discovered a material that could use light to bring together different computing functions into one component, leading to all-optical systems.

Computers currently use electrons to transfer information and process applications. On the other hand, data sources such as the internet rely on optical systems; the transfer of information using light. Optical fibres are used to send information around the world at the speed of light, but these signals then have to be converted to electrical signals once they reach a computer, causing a significant slowdown in processing.

Abstract

Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary difficulty in obtaining n-type conductivity. The ability to form chalcogenide glass p-n junctions could improve the performance of phase-change memory and thermoelectric devices and allow the direct electronic control of nonlinear optical devices. Previously, carrier-type reversal has been restricted to the GeCh (Ch=S, Se, Te) family of glasses, with very high Bi or Pb ‘doping’ concentrations (~5–11 at.%), incorporated during high-temperature glass melting. Here we report the first n-type doping of chalcogenide glasses by ion implantation of Bi into ​GeTe and GaLaSO amorphous films, demonstrating rectification and photocurrent in a Bi-implanted GaLaSO device. The electrical doping effect of Bi is observed at a 100 times lower concentration than for Bi melt-doped GeCh glasses

15 pages of supplemental information

Progress to fully optical computing and faster hybrid computing

New research has demonstrated how glass can be manipulated to create a material that will allow computers to transfer information using light. This development could significantly increase computer processing speeds and power in the future.

The challenge was to find a single material that can effectively use and control light to carry information around a computer. Much like how the web uses light to deliver information, we want to use light to both deliver and process computer data.

“This has eluded researchers for decades, but now we have now shown how a widely used glass can be manipulated to conduct negative electrons, as well as positive charges, creating what are known as ‘pn-junction’ devices. This should enable the material to act as a light source, a light guide and a light detector – something that can carry and interpret optical information. In doing so, this could transform the computers of tomorrow, allowing them to effectively process information at much faster speeds.”

The researchers expect that the results of this research will be integrated into computers within ten years. In the short term, the glass is already being developed and used in next-generation computer memory technology known as CRAM, which may ultimately be integrated with the advances reported.

CRAM is a kind of phase change memory Phase-change memory (also known as PCM, PCME, PRAM, PCRAM, Ovonic Unified Memory, Chalcogenide RAM and C-RAM) is a type of non-volatile random-access memory. PRAMs exploit the unique behaviour of chalcogenide glass. In the older generation of PCM heat produced by the passage of an electric current through a heating element generally made of TiN would be used to either quickly heat and quench the glass, making it amorphous, or to hold it in its crystallization temperature range for some time, thereby switching it to a crystalline state.

Nature Communication – n-type chalcogenides by ion implantation

The research by the University of Surrey, in collaboration with the University of Cambridge and the University of Southampton, has found it is possible to change the electronic properties of amorphous chalcogenides, a glass material integral to data technologies such as CDs and DVDs. By using a technique called ion doping, the team of researchers have discovered a material that could use light to bring together different computing functions into one component, leading to all-optical systems.

Computers currently use electrons to transfer information and process applications. On the other hand, data sources such as the internet rely on optical systems; the transfer of information using light. Optical fibres are used to send information around the world at the speed of light, but these signals then have to be converted to electrical signals once they reach a computer, causing a significant slowdown in processing.

Abstract

Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary difficulty in obtaining n-type conductivity. The ability to form chalcogenide glass p-n junctions could improve the performance of phase-change memory and thermoelectric devices and allow the direct electronic control of nonlinear optical devices. Previously, carrier-type reversal has been restricted to the GeCh (Ch=S, Se, Te) family of glasses, with very high Bi or Pb ‘doping’ concentrations (~5–11 at.%), incorporated during high-temperature glass melting. Here we report the first n-type doping of chalcogenide glasses by ion implantation of Bi into ​GeTe and GaLaSO amorphous films, demonstrating rectification and photocurrent in a Bi-implanted GaLaSO device. The electrical doping effect of Bi is observed at a 100 times lower concentration than for Bi melt-doped GeCh glasses

15 pages of supplemental information