Injection mechanism at contacts in a quantum-well intersubband infrared detector

The role of the contact electrodes on the detection mechanisms in quantum-well photoconductors is usually overlooked. We show that these contacts may be blocking in a large temperature range. Upon illumination, the electric field is enhanced at the cathode electrode so that the injected current meets the quantum-well requirement. This mechanism is demonstrated in a single quantum-well photoconductor by the detailed study of the photocurrent over dark current ratios and by photocapacitance measurements.