Mid-Infrared Interband Cascade Photodetectors With Different Absorber Designs

We report an experimental investigation on the influence of absorber thicknesses in mid-infrared interband cascade (IC) photodetectors. The electrical and optical properties of these five-stage IC detectors are characterized in detail over a wide operating temperature range. The IC detectors are operational above 400 K under zero bias, with a 50% cutoff of 4.56 mu m and external quantum efficiency (single pass, no antireflection coating) up to 10.1% at room temperature. The dark current in the IC detectors is at 10 mu A/cm(2) at -10 mV, with a Johnson-limited D* of 1.10 x 10(11) Jones at 200 K. Our experimental results show that both the optical response and the noise performance in the quantum-engineered IC detectors improve with increased discrete absorber thicknesses. It is also suggested that the dark current in the IC detectors is determined by tunneling components at lower temperatures, and becomes diffusion-limited at higher temperatures.