Heterostructures for achieving large responsivity in InAs/GaAs quantum dot infrared photodetectors

Quantum dot infrared photodetectors (QDIPs) offer normal-incidence detection, low dark current, high operating temperature, and multi-wavelength detection. In an effort to get better responsivity in QDIPs at higher operating temperatures, we have grown, fabricated, and characterized two different QDIP heterostructures. The first is a device with 70 quantum dot layers. As a result, the peak responsivity is measured to be 0.12 A/W for Vbias=2.0 V and T=175 K. The second device has ten layers of InAs quantum dots embedded in an AlAs/GaAs superlattice. As a result of the subsequent large dot density and increased carrier confinement, the peak responsivity is measured to be 2.5 A/W for Vbias=−1.5 V and T=78 K.