Development towards higher operating temperature, smaller pitch and larger format arrays is ongoing for midwave (MW) InAs/GaSb superlattice detectors at IRnova. One part of this effort entails improvement in the MW detector design, which has resulted in increased quantum efficiency to 55-60 % in the entire 3-5 μm wavelength region, with dark current levels lower than 3×10-6 A/cm2 at 120 K. Furthermore, MW-MW dual band detectors have been realized by using pixel filters fabricated on top of regular MW FPAs. The pixel filters were designed to transmit infrared radiation in the 3.5 μm - 4.1 μm wavelength region and to completely block light shorter than 3.5 μm. By comparing the signals of filtered and unfiltered pixels, excellent contrast between the two bands were obtained. Long wave infrared detectors have also been realized with cut-off wavelength at 12.2 μm and dark current levels following the Rule07 trendline from 80 K to 160 K, with only two times higher dark current than Rule07 at 80 K.
Continuing with its legacy of producing high performance infrared detectors, IRnova introduces its high resolution LWIR IDDCA (Integrated Detector Dewar Cooler assembly) based on QWIP (quantum well infrared photodetector) technology. The Focal Plane Array (FPA) has 640×512 pixels, with small (15μm) pixel pitch, and is based on the FLIRIndigo ISC0403 Readout Integrated Circuit (ROIC). The QWIP epitaxial structures are grown by metal-organic vapor phase epitaxy (MOVPE) at IRnova. Detector stability and response uniformity inherent to III/V based material will be demonstrated in terms of high performing detectors. Results showing low NETD at high frame rate will be presented. This makes it one of the first 15μm pitch QWIP based LWIR IDDCA commercially available on the market. High operability and stability of our other QWIP based products will also be shared.
We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells.
IRnova has a long history of producing QWIPs for the LWIR band. In this paper we give an overview of the current
products (FPAs with 640x480 and 384x288 pixels respectively, and 25 μm pitch) and their performance. Their superior
stability and uniformity inherent to detectors based on III/V material system will be demonstrated. Furthermore, an
IDCA specifically designed for hand-held systems used for the detection of SF6 gas using a 0.5 W cooler will be
presented. The detector format is 320x256 pixels with 30 μm pitch using the ISC9705 read out circuit. The peak
wavelength is at 10.55 μm and the NETD is 22 mK.
IRnova has been manufacturing mid wave infrared (MWIR) detectors based on InAs/GaSb type-II superlattices (T2SL)
since 2014. Results from the first years of production of MWIR focal plane arrays (FPAs) with 320 x 256 pixels on 30
μm pitch using the ISC9705 readout integrated circuit (ROIC) is presented in terms of operability, temporal and spatial
noise equivalent temperature difference (NETD) and other key production parameters. Results on image stability of
T2SL detectors show that no deterioration of image quality over time can be observed. Furthermore it is shown that the
non-uniformity correction remains stable even after repeated detector temperature cycles. Spatial and temporal NETD
for fabricated mid wave arrays show a temporal NETD of 12 mK and a spatial NETD of 4 mK with f/2 optics and 8 ms
integration time. When studied over a large scene temperature, the spatial noise is still less than 60 % of the temporal
noise. Furthermore, 640 x 512 mid wave FPAs with 15 μm pitch using the ISC0403 ROIC are entering an
industrialization phase. Temporal and spatial NETD values of 25 mK and 10 mK, respectively, are obtained with f/4
optics and 22 ms integration time and the operability is 99.85 %. A status update on the development of T2SL detectors
for short wave, mid wave and long wave infrared wavelength regions for existing and new applications is given and
recent development towards higher operating temperature, smaller pitch and larger FPA formats is presented.
A simple method of growing large areas of InP on Si through Epitaxial Lateral Overgrowth (ELOG) is
presented. Isolated areas of high quality InP suitable for photonic integration are grown in deeply etched SiO2
mask fabricated using conventional optical lithography and reactive ion etching. This method is particularly
attractive for monolithically integrating laser sources grown on InP with Si/SiO2 waveguide structure as the
mask. The high optical quality of multi quantum well (MQW) layers grown on the ELOG layer is promisingly
supportive of the feasibility of this method for mass production.