CHARACTERISTICS OF PHOTOVOLTAIC WAVELENGTH-TUNABLE SUPERLATTICE INFRARED PHOTODETECTOR

摘要

A simple wavelength-tunable infrared photodetector containing a superlattice and a single current blocking layer sandwiched by two heavily doped contact layers was investigated. The switch of detection wavelength is realized by the current blocking layer that serves as an energy filter. Under low bias, the conduction by the photo-excited carriers in the second miniband minimum is suppressed, and is primarily due to the carriers in the second miniband maximum. While bias increased, those suppressed carriers can tunnel through the current blocking layer and contribute to the photocurrent. The measured peak detectivity of this detector is 2.6X10~9 cmHz~(0.5)/W (9.7 μm) at -0.6V and is 1.1X10~(10) cmHz~(0.5)/W (6.7 μm) at -0.1V at 45K. In addition, it can be operated in photovoltaic mode. These show that the superlattice is a flexible structure for an infrared detector.