nBn extended short-wavelength infrared focal plane array

Abstract

An extended short-wavelength nBn InAs/GaSb/AlSb type-II superlattice-based infrared focal plane array imager was demonstrated. A newly developed InAsSb/GaSb superlattice design was used as the large-bandgap electron barrier in this photodetector. The large band gap electron-barrier design in this nBn photodetector architecture leads to the device having lower dark current densities. A new bi-layer etch-stop scheme using a combination of InAsSb bulk and AlAsSb/GaSb superlattice layers was introduced to allow complete substrate removal and a shorter wavelength cut-on. Test pixels exhibit 100% cutoff wavelengths of ∼2.30 and ∼2.48 μm at 150 and 300 K, respectively. The devices achieve saturated quantum efficiency values of 59.7% and 63.8% at 150 and 300 K, respectively, under backside illumination and without any antireflection coating. At 150 K, photodetectors exhibit dark current density of 8.75×10 A/cm under -400 mV applied bias, providing specific detectivity of 2.82×10 cm·Hz/W at 1.78 μm. At 300 K, the dark current density reaches 4.75×10 A/cm under -200 mV bias, providing a specific detectivity of 8.55×10 cm·Hz/W 1.78 μm.

Type–II superlattices base visible/extended short–wavelength infrared photodetectors with a bandstructure–engineered photo–generated carrier extractor

“…The superlattice was designed using the empirical tight–binding model (ETBM) 25 . The photo−generated carrier transport inside the absorption region relies entirely on diffusion; thus, the new photo–generated carrier extractor does not require the applied bias which is required by other unipolar photodetector structures, such as nBn and pMp 17,26,27 ; as such, it functions under zero bias like a conventional pn junction photodetector.

Figure 1Schematic diagram of conduction (E C ) and valence (E V ) bands of the visible/e–SWIR photodetector at 150K, with a bandstructure–engineered photo–generated carrier extractor. Section 1, 2, 3, 4, and 5 of the device have ~760, 580, 715, 1040, and 800 meV bandgap, respectively.

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A dual-band graphene/silicon nanowire array heterojunction photodetector induced by leaky mode resonances

“…For instance, two-dimensional materials are often grown using typical vapor transport processes, 8,9 plasma enhanced chemical vapor deposition (PECVD), 10 metal-organic chemical vapor deposition (MOCVD) 11 and molecular beam epitaxy (MBE). 12 They represent complex and costly preparation processes. By contrast, silicon is an ideal option for light detection due to its high carrier mobility, good stability and established silicon-based semiconductor manufacturing processes.…”

Toward Ga‐Free Wavelength Extended 2.6 µm InAsP Photodetectors with High Performance

“…Short-wavelength infrared (SWIR) photodetectors working in the spectral range of 1−3 μm have substantial potential applications, such as remote sensing, night vision imaging, environmental monitoring, and eye-safe light detection and ranging (LiDAR). [1][2][3][4] SWIR offers several distinctive advantages InGaAs, InAlAs, and InAsP have been fabricated with extended cut-off wavelengths of 2.6−3.0 μm at 300 K. [7,8] The formation of 60°misfit dislocations with a/2<110>{111} slip system at mismatched metamorphic layer interfaces and their glide can lead to an effective strain relaxation, thereby fabricating a virtual substrate with the desired lattice constant. [8] In comparison to latticematched InGaAs detectors, extended In x Ga 1-x As detectors yield a higher dark current and lower responsivity owing to larger nonradiative recombination, including the Shockley-Read-Hall process mediated by crystal defects and an Auger process dominant in a narrow-bandgap InGaAs absorber.…”

“…Short‐wavelength infrared (SWIR) photodetectors working in the spectral range of 1−3 µm have substantial potential applications, such as remote sensing, night vision imaging, environmental monitoring, and eye‐safe light detection and ranging (LiDAR). [ 1–4 ] SWIR offers several distinctive advantages compared to mid‐wavelength (3−5 µm) and long‐wavelength (8−12 µm) IRs. Similar to the reflection/absorption pattern of visible light, SWIR light is reflected and/or absorbed at the surface of an object, leading to improved sharpness and recognition accuracy in IR imagery.…”