US funds spark holey laser study

26 Feb 2008

An academic collaboration with Bell Labs will initially make GaAs quantum cascade lasers, but the long-term aim is to fabricate an electrically-pumped silicon laser.

Oana Malis

A New York professor has been granted $300,000 by the US National Science Foundation in the hope of producing the first quantum cascade laser based exclusively on hole transport.

Oana Malis of Binghamton University says that her research could make SiGe the basis for such a device in the future, which could in turn lead to the first electrically pumped silicon laser.

However, the initial project will focus on carbon-doped nanostructures containing alternating GaAs and AlAs layers, which are intended to emit 5-10 µm wavelength infrared light.

The surface-emitting devices will be fabricated at Alcatel-Lucent's Bell Labs by Loren Pfeiffer, who Malis describes as "a world leader in the MBE growth of high-purity GaAs".

Malis and Pfeiffer are currently performing initial research in the three-year project, for which the main material target is producing infrared VCSELS for spectroscopic gas detection.

The money will be spent on the day-to-day running of what will be quite fundamental research, Malis told compoundsemiconductor.net.

"The project will focus on enhancing the understanding of the physics of hole intersubband transitions and of ultrafast hole relaxation processes in the context of a well developed semiconductor system where material quality issues are minimized," she explained.

"This investigation will also advance the understanding of basic mechanisms involved in molecular beam epitaxy of nanostructures and in growth of high-purity carbon-doped GaAs."

The Binghamton-Bell Labs team will also be investigating infrared quantum cascade lasers (QCLs) made from InAlN/GaN layers and has earned a $44,244 grant from Research Corporation for this effort.

This project will study the feasibility of making nitride-based QCLs, which is in part a question of epitaxy because "the growth of InAlN/GaN by MBE is fairly challenging", according to Malis.

Michael Manfra, the Bell Labs scientist who will be fabricating the devices, will use about 15% indium content to lattice match the InAlN layers with GaN.