GaSb-based infrared (IR) photodetector technology progression is toward larger-format focal plane arrays (FPAs). This requires a performance-based and cost-based manufacturing process on larger diameter substrates for improved throughput, volume, and yield. IQE has demonstrated molecular beam epitaxy (MBE) growth processes for barrier-design detectors (nBn) in multi-wafer configurations on 4-inch and 5-inch diameter GaSb substrates, and via a metamorphic process on 4-inch and 6-inch GaAs substrates. Recently we took the next step in this progression, growing nBn detectors on 6-inch Si substrates coated with CVD-grown Ge, opening the door for potential integration with Si-based electronic circuitry. Here, we compare the epiwafer characteristics (morphology, x-ray, PL) and diode performance (turn-on, QE, cutoff wavelength) of this M-nBn on Ge-Si with the same M-nBn on GaAs and the corresponding nBn structure grown on native GaSb substrate. Similar performance was obtained on all three types of substrates. We also present FPA data based on a 640×512 pixel, 15 μm pitch process without substrate removal, where QE ~ 80%, NE▵T < 20 mK, and operability <99% was demonstrated. The results represent an important technological path toward next-generation large-format IR detector array applications.
We report the experimental results of a 40-stage InP-based quantum cascade laser (QCL) structure grown on a 6-inch GaAs substrate with metamorphic buffer (M-buffer). The laser structure’s strain-balanced active region was composed of Al0.78In0.22As/In0.73Ga0.27As and an all-InP, 8 μm-thick waveguide. The wafer was processed into ridge-waveguide chips (3mm x 30 μm devices) with lateral current injection scheme. Devices with high reflection coating delivered power in excess of 200 mW of total peak power at 78K, with lasing observed up to 230K. Preliminary reliability testing at maximum power showed no sign of performance degradation after 200 minutes of runtime. Measured characteristic temperatures of T0 ≈ 460 K and T1 ≈ 210 K describes the temperature dependence for threshold current and slope efficiency, respectively, in the range from 78K to 230K. Partial high reflection coating was used on the front facet to extend the lasing range up to 303K.