Advances in large-area Hg 1-x Cd x Te photovoltaic detectors for remote sensing applications

Abstract

State-of-the-art large area photovoltaic detectors fabricated in HgCdTe grown by Molecular Beam Epitaxy have been demonstrated for the Crosstrack Infrared Sounder (CrIS) instrument. Large area devices (1 mm in diameter) yielded excellent electrical and optical performance operating at 81K for LWIR band and at 98K for MW and SWIR bands. LWIR and MWIR detectors have near-theoretical electrical performance, and AR-coated quantum efficiency is greater than 0.70. Measured average R o A at 98K is 2.0E7 Ω-cm 2 and near-theoretical quantum efficiencies greater than 0.90 were obtained on SWIR detectors. These state-of-the-art large area photovoltaic detector results reflect high quality HgCdTe grown by Molecular Beam Epitaxy on CdZnTe substrates in all three spectral bands of interest.

Analysis of Current–Voltage Measurements on Long-Wavelength HgCdTe Photodiodes Fabricated on Si Composite Substrates

“…17 The measured peak wavelength (k p ) was 9 lm, and the cutoff wavelength was 10 lm, which is roughly 10% longer than k p , indicating a sharp fall-off. 16 Detector QE is defined as the ratio of the number of minority carriers collected by the detector to the number of photons incident on the detector. Under backside illumination conditions, photons passed first through Si [which has a reflectivity of R(k) = 0.33, where k is the wavelength of the incident photons], then through the neutral n-region (QE = g h ), then through the depletion region (QE = g dw ), and finally through the neutral p-region (QE = g e ).…”

“…Details of the fabrication process have been reported elsewhere. 16 These fabricated devices were then characterized electrically and optically at 78 K, and in some cases as a function of temperature, to understand various current contributions. Backside illumination was used for all optical measurements, as indicated by Fig.…”

Infrared detectors overview in the short-wave infrared to far-infrared for CLARREO mission

“…Quantum efficiency vs wavelength was determined on all of the detectors under backside-illuminated condition. Observed dips at near 4.2 µm and near 5.5 to 6.2 µm wavelengths are due to atmospheric CO 2 absorption bands and are a measurement system artifact 13 . …”

“…Previously, Teledyne Technologies fabricated state-of-the-art large area photovoltaic HgCdTe detectors grown by Molecular Beam Epitaxy and demonstrated their performance characteristics for the CrIS instrument 13 . Figure 4 shows quantum efficiency vs wavelength for the three spectrally separate SWIR, MWIR and LWIR detectors and flat spectral QE was determined in each spectral band.…”

“…We will discuss the commercially available detectors, in addition to on-going detector technology development efforts in the SWIR to Far-IR 12 . Conversely, Teledyne Technologies developed the PV HgCdTe detectors for the CrIS mission applications in the 3.5-to15.4-µm region 13 .…”