Demonstration of 640 · 512 pixels long-wavelength infrared (LWIR) quantum dot infrared photodetector (QDIP) imaging focal plane array q S.D. Gunapala a, * , S.V. Bandara a , C.J. Hill a , D.Z. Ting a , J.K. Liu a , S.B. Rafol b , E.R. Blazejewski a , J.M. Mumolo a , S.A. Keo a , S. Krishna c , Y.-C. Chang a,1 , C.A. Shott d a The Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States b The Infravision Systems, 2400 Lincoln Avenue, Altadena, CA 91001, United States c University of New Mexico, 1313 Goddard Street SE, Albuquerque, NM 87106, United States d The FLIR Systems Inc., Indigo Operations, 70 Castilian Dr., Goleta, CA 93117, United States Available online 8 December 2006 Abstract We have exploited the artificial atom-like properties of epitaxially grown self-assembled quantum dots (QDs) for the development of high operating temperature long wavelength infrared (LWIR) focal plane arrays (FPAs). QD infrared photodetectors (QDIPs) are expected to outperform quantum well infrared detectors (QWIPs) and are expected to offer significant advantages over II–VI material based FPAs. We have used molecular beam epitaxy (MBE) technology to grow multi-layer LWIR dot-in-a-well (DWELL) structures based on the InAs/InGaAs/GaAs material system. This hybrid quantum dot/quantum well device offers additional control in wavelength tuning via control of dot-size and/or quantum well sizes. DWELL QDIPs were also experimentally shown to absorb both 45° and nor- mally incident light. Thus we have employed a reflection grating structure to further enhance the quantum efficiency. The most recent devices exhibit peak responsivity out to 8.1 lm. Peak detectivity of the 8.1 lm devices has reached 1 · 10 10 Jones at 77 K. Furthermore, we have fabricated the first long-wavelength 640 · 512 pixels QDIP imaging FPA. This QDIP FPA has produced excellent infrared imag- ery with noise equivalent temperature difference of 40 mK at 60 K operating temperature. Ó 2006 Elsevier B.V. All rights reserved. 1. Introduction The artificial atom-like properties of epitaxially self- assembled quantum dots (QDs) were exploited in this work for the development of high operating temperature long wavelength infrared (LWIR) focal plane arrays (FPAs). QDs are nanometer-scale islands that form spontaneously on a semiconductor substrate due to lattice mismatch. QDIPs are expected to have significant advantages over quantum well infrared detectors (QWIPs) [1–8]. QD infra- red photodetectors (QDIPs) are fabricated using robust wide band gap III–V materials which are well suited to the production of highly uniform LWIR arrays. QD based infrared photodetectors have the potential to make a signif- icant impact on the next generation of infrared imaging systems. QDIPs possess all of the advantages of traditional III–V based infrared photodetectors, such as: extremely high operability, mature fabrication technology, very large formats, and material production that is increasingly high volume and low cost. The addition of active nanoscale par- ticles (i.e. QDs) embedded within the III–V infrared detec- tor allows for higher operating temperatures and increased band gap tunability without sacrificing the economic advantages of the mature III–V infrared imaging system pipeline. 1350-4495/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.infrared.2006.10.004 q The research described in this paper was performed by the Jet Propulsion Laboratory, California Institute of Technology. * Corresponding author. E-mail address: sarath.d.gunapala@jpl.nasa.gov (S.D. Gunapala). 1 Permanent address: Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States. www.elsevier.com/locate/infrared Infrared Physics & Technology 50 (2007) 149–155