2.4m cutoff wavelength heterojunction phototransistor with strained InAs/InGaAs MQW absorption layer

A novel mid-infrared photodetector has been developed that consists of an InP/InGaAs heterojunction phototransistor with a strained InAs/InGaAs multi-quantum well (MQW) absorption layer inserted in the low electric field region of the collector. The thick strained InAs well enhances the quantum confined effect. This provides a high absorption coefficient at a wavelength of 2.3m. The photocurrent generated in the MQW absorption layer is amplified by the current gain, resulting in a high responsivity of more than 10A/W. In addition, the small volume of the MQW in the low electric field region provides a low dark current.