Lasing is reported for ridge-waveguide devices processed from a 40-stage InP-based quantum cascade laser structure grown on a 6-inch silicon substrate with a metamorphic buffer. The structure used in the proof-of-concept experiment had a typical design, including an AlInAs/InGaAs strain-balanced composition, with high strain both in quantum wells and barriers relative to InP, and an all-InP waveguide with a total thickness of 8 µm. Devices of size 3 mm x 40 µm, with a high-reflection back facet coating, emitted at 4.35 µm and had a threshold current of approximately 2.2 A at 78 K. Lasing was observed up to 170 K. Compared to earlier demonstrated InP-based quantum cascade lasers monolithically integrated onto GaAs, the same laser structure integrated on silicon had a lower yield and reliability. Surface morphology analysis suggests that both can be significantly improved by reducing strain for the active region layers relative to InP bulk waveguide layers surrounding the laser core.

Experimental data for an InP-based 40-stage quantum cascade laser structure grown on a 6-in. GaAs substrate with a metamorphic buffer are reported. The laser structure had an Al0.78In0.22As/In0.73Ga0.27As strain-balanced active region composition and an 8 μm-thick, all-InP waveguide. High reflection coated 3 mm × 30 μm devices processed from the wafer into a ridge-waveguide configuration with a lateral current injection scheme delivered over 200 mW of total peak power at 78 K with lasing observed up to 170 K. No signs of performance degradation were observed during a preliminary 200-min reliability testing. Temperature dependence for threshold current and slope efficiency in the range from 78 K to 230 K can be described with characteristic temperatures of T0 ≈ 460 K and T1 ≈ 210 K, respectively. Lasing was extended to 303 K by applying a partial high reflection coating to the front facet of the laser.

GaSb-based infrared (IR) photodetector structures were grown on large diameter, 150 mm, Si substrates using a multistep metamorphic buffer architecture process. A standard bulk InAsSb/AlAsSb barrier detector design with a cutoff wavelength of ∼4 μm was used as a test vehicle for this growth process. First, a Ge layer was deposited by chemical vapor deposition, creating a Ge-Si substrate for the subsequent molecular beam epitaxy growth of the remaining III–V buffer and device layers. X-ray diffraction and photoluminescence measurements demonstrated high crystal quality and excellent cross-wafer uniformity of the device epiwafer characteristics. Microscopy evaluation revealed a moundlike surface morphology with a low root-mean-square roughness value below 2 nm, suitable for focal plane array (FPA) fabrication. Large-area mesa diode test devices measured dark currents of 5 × 10−5 A/cm2 and a quantum efficiency of 60% for the Sb-detector grown on Ge–Si. The same structure was fully fabricated into a standard FPA and produced good imagery resolution with high operability. These excellent results for this first FPA manufactured from an Sb-photodetector grown on Si using this Ge-Si architecture demonstrate a promising path in the progression of Sb-IR technology as it transitions from development to next-generation, large-format IR manufacturing with an eye toward potential heterogeneous integration with silicon.

High peak power, room-temperature operation in the long wave infrared spectral region is reported for double-channel, ridge waveguide quantum cascade lasers (QCLs) monolithically integrated onto a silicon substrate. The 55-stage laser structure with an AlInAs/InGaAs core and InP cladding was grown by molecular beam epitaxy directly onto an 8-in. diameter germanium-coated silicon substrate template via a III–V alloy metamorphic buffer. Atomic force microscope imaging demonstrated a good quality surface for the full QCL structure grown on silicon, with improved roughness over wider areas compared to the previous work. Fabricated 3 mm × 26  μm lasers operate at room temperature, deliver more than 3 W of peak (6 mW of average) optical power, and show approximately 3% wall plug efficiency and 4.3 kA/cm2 threshold current density with emission wavelength centered at 11.5  μm. The lasers had a high yield with only around 15% max power deviation and no signs of performance degradation were observed over a 10 h burn in period at maximum power. Singled-lobed high quality output beam with M2 = 1.36 was measured for 3 mm × 22  μm devices, demonstrating that it is possible to produce high-brightness quantum cascade lasers on silicon with standard ridge waveguide processing paving the way for low-cost production of integrated mid-infrared platforms.

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