Nanostructure Technology for EO/IR Detector Applications

Abstract

This chapter covers recent advances in the development of nanostructurebased material technologies to benefit next-generation electro-optical (EO) and infrared (IR) sensor and imager applications. Nanostructured materials can now be integrated into a variety of technological platforms, offering novel optoelectrical properties that greatly enhance device performance in many practical applications. Use of novel carbon nanotube (CNT) based materials has enabled new approaches for applying nanostructure design methodologies that can offer enhanced performance for low-cost bolometers for IR detection and imaging applications. We will discuss the development of carbon nanostructure based infrared detectors and arrays, including concepts that will provide high performance, high frame rate, and uncooled microbolometers for mid-wave infrared (MWIR) and long-wave infrared (LWIR) band detection. In addition, nanostructured antireflection (AR) coatings are being developed that significantly enhance transmission over a broad spectrum, providing substantial improvements in device performance compared to conventional thin film AR coatings. These nanostructured AR coatings have been demonstrated over visible to LWIR spectral bands on various substrates. In this chapter, we discuss both theoretical and measured results of these diverse nanostructure technologies to advance sensing performance over a wide range of spectral bands for defense, space, and commercial applications.

Advanced detector performance from UV to IR with nanostructured antireflection coatings

“…We have previously developed and demonstrated nanostructured AR coatings on GaSb substrates designed for the 3-5 µm MWIR band. 2,5 One such a two-layer MWIR coating, with layer structure shown in Figure 3, inset, comprised layers of nanostructured SiO2 and Si deposited on a GaSb substrate. The inferred layer thicknesses and infrared refractive index values for the Si and SiO2 layers from fitting the measured reflectance data are, respectively: tSi ~ 420 nm and nSi ~ 2.37; and tSiO2 ~ 780 nm and nSiO2 ~ 1.44.…”

Doping and Transfer of High Mobility Graphene Bilayers for Room Temperature Mid-Wave Infrared Photodetectors

“…HgCdTe, or MCT, the most widely used infrared (IR) detector material in military applications, is a direct energy bandgap semiconductor having a bandgap that is tunable from near-infrared (NIR) and SWIR to VLWIR bands through varying the Cd composition [15]. Typically, 0.3:0.7 Cd:Hg ratio results in a detectivity window over the SWIR to MWIR wavelength range.…”

Advanced nanostructured antireflection coatings for high performances IR detector and imaging applications

“…The formation of the nanostructured thin films results from surface diffusion and self-shadowing effects during an off-angle growth process [Figure 1(b)]. 6,7 Random growth fluctuations on the substrate produce shadow regions that incident vapor flux cannot reach while creating nonshadow regions where incident flux deposits preferentially to form oriented nanorods with lower densities and reduced effective refractive indexes that are tilted relative to the sample surface. [8][9][10] Because the gaps between these nanostructures can be made smaller than the wavelengths of IR and visible radiation, a…”