Summary:

Nanolight is pursuing a Phase I for improving the deposition of IV-VI (lead salts) substrates for mid-wavelength infrared (MWIR) to long-wavelength infrared (LWIR) laser diodes and detectors. The pursuit of this substrate is a revivification of an earlier R&D push in the 70s, when, for fabrication difficulties, it was dropped in favor of mercury cadmium telluride (HgCdTe).

Technology Description:

Nanolight is pursuing a "revolutionary" method for epitaxial deposition of IV-VI compounds, such as Pb1-xSnxSe (lead tin selenide), on a silicon substrate with a fluoride buffer layer. The main advantages of IV-VI Pb-salt semiconductors include:
• A large dielectric constant, which helps to screen and localize the defect-related effects.
• Uniformity of the epitaxial material, which ensures that the cutoff wavelength is high. This reduces the demand for powerful signal processing read-out integrated circuits (ROICs).
• Low growth temperature; this allows direct growth of Pb-salt detector structure on Si with ROIC. Therefore, a cost-effective, monolithic focal plane array (FPA) can be fabricated on Si substrate. Two-color simultaneous waveband operation and large formats of FPA can also be fabricated with this method.

This is early Phase I work, with the company collaborating with the Opto-electronics Group at the University of Oklahoma (OU) and others to develop PbSnSe focal plane arrays (FPAs) for use in infrared cameras. A complete prototype is to be developed within two to three years.

MDA Origins:

MDA awarded Nanolight the Phase I SBIR on the strength of its technology's promise in solving device performance issues. MDA is interested in MWIR- and LWIR-range sensors for providing an effective means of identifying unique target signatures, such as missile emission, enabling sensor systems based on mid-IR detectors with high quantum efficiency in the mid-IR wavelength range to provide effective early warning and interceptor guidance against missile threats for a wide range of ground vehicles and aircraft.

Spinoff Applications:

Detection of light emitted in the MWIR wavelength region of the spectrum has widespread applications including night vision, trace gas sensing for chemical and explosives detection, pollution devices, Homeland Security applications, and basic spectrometry. The MWIR region in particular is sensitive for many biologically relevant molecules, such as NH3 (ammonia), greenhouse gases, and chem/bio warfare agents.

In the far future, the company sees a potential to integrate both laser and detector on the same substrate, assuming optical path problems can be solved, resulting in a truly "monolithic" device.

Commercialization:

This is early work with much emphasis on academic and industrial research; a prototype MWIR focal plane array is anticipated to be two to three years away.

Company Profile:

Nanolight, Inc., is at present a three-person shop, and it offers epitaxial services using a customer-designed molecular-beam epitaxy (MBE) system housed in the Opto-electronic Group's laboratories at the University of Oklahoma (OU), through an agreement with OU. Such services are of small-scale and of industrial nature. This MBE system produces very high-purity epitaxial layers with abrupt interfaces, good control of thickness of layers, doping, and composition.

Contact Information:

Dr. Zhisheng Shi
Nanolight, Inc.
710 Asp Avenue, Suite 303
Norman, OK 73069
(405) 579-5662
email: shi@ou.edu
web: www.nano-light.com