Future NASA earth science systems and missions, specifically those involving high resolution Lidar measurements, will benefit from the development of large-area, high gain AlGaN ultraviolet avalanche photodiodes (UV-APD) arrays operating at room temperature at the 355 nm wavelength. The high quality GaN/AlGaN UV-APD detector arrays are epitaxially grown using an optimized metal organic chemical vapor deposition (MOCVD) technique. The use of lattice-matched bulk GaN substrates provides low dark/leakage current by minimizing defects from the substrate, while alternately AlN substrates can be used to provide backside-illuminated, high fill factor UV-APD devices. In addition to low dark current noise, the solid-state UV-APD devices demonstrate high quantum efficiencies with very high avalanche gains (>10^5). For the Phase II SBIR effort, we shall model, design, develop, and demonstrate the AlGaN UV-APD array technology for implementation in future NASA missions. We will work with NASA for modelling UV-APD arrays for performance improvements in NASA Earth Science systems. Magnolia will collaborate with Prof. Russ Dupuis of Georgia Tech, an expert in III-N material growth and device technology, for MOCVD growth, fabrication, and characterization of the UV-APD array devices. This will entail the enhancement of surface passivation techniques for further performance improvements, developing high quality, low resistivity n- and p-type contacts, as well as incorporating antireflection coatings. It is expected based on measurement data that these devices can perform in Geiger-mode at ~355 nm with high single-photon detection efficiencies for operation in photon-starved environments. Based in part on results attained from the Phase I effort, the AlGaN-based UV-APD technology can meet and/or exceed system requirements in applications such as high resolution Lidar to benefit NASA systems for advancing future missions
Potential NASA Commercial Applications: (Limit 1500 characters, approximately 150 words) Future NASA missions will require high gain UVAPD large area detector arrays.The NASA earth science application for the AlGaN UV-APD arrays. operating at the 355 nm UV band is of interest for high resolution Lidar systems. To resolve extremely weak/distant signals in such applications, detector arrays with large areas and very high gains are required. The objective of the Proposed NASA Phase II SBIR is to model, design, and develop the necessary technology for high performance GaN/AlGaN UV-APDs that can be implemented in future NASA missions. The technology developed under the proposed Phase II SBIR Program can also be applied to other NASA measurement instruments. The implementation of the technology can benefit situations requiring replacement aging and/or proprietary technologies with compact, less costly solid-state solutions. As part of the Phase II SBIR effort, we will work with NASA Program Manager towards application of the UV-APDs for other NASA programs and missions. The AlGaN-based UV-APDs allow band gap engineering for fine-tuning of the operating wavelength to UV band of interest. The solid-state UV-APDs devices are also radiation hardened and offer high chemical and thermal stability, making them well-suited for harsh operating conditions and environments such as in space-based applications. Such applications could include ozone/pollutant monitoring, and measurement of UV signatures
Potential NON-NASA Commercial Applications:
: (Limit 1500 characters, approximately 150 words) UV Detectors and Sensors are useful in a wide variety of industrial, military, and scientific applications where detection of UV radiation plays a key role. Most of these applications for UV detection and/or measurement require high performance UV-APD detector arrays and sensor systems. Ultraviolet APD arrays with high gain can capture unique target signatures, which provide critical information for applications that include machine vision, threat warning, and chemical and biological applications for detection of surface residues and biological agents. Within the Defense applications of interest are UV sensing devices to identify chemical/biological threats to war-fighters, early missile threat warning systems, and jet flame/engine monitoring. This market is segmented into four broad sectors: industrial, consumer electronics, automotive, and medical. A number of these commercial applications can directly benefit from the performance capabilities and features of the AlGaN UV-APD detector technology. Such applications include UV sensors in automobiles for improved safety, stability, and performance; detection of arcing and corona discharge in power-lines and industrial monitoring of UV radiation. In addition, the commercial UV sensor market is projected to grow substantially over the next 10 years.
Technology Taxonomy Mapping: (NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.) Characterization Detectors (see also Sensors) Lasers (Ladar/Lidar) Materials & Structures (including Optoelectronics) Materials (Insulator, Semiconductor, Substrate) Models & Simulations (see also Testing & Evaluation) Optical/Photonic (see also Photonics) Prototyping Smart/Multifunctional Materials Ultraviolet
