The concept of leaky electronic states in the continuum is used to achieve room temperature operation of photovoltaic superlattice infrared photodetectors. A structural asymmetric InGaAs/InAlAs potential profile is designed to create states in the continuum with the preferential direction for electron extraction and, consequently, to obtain photovoltaic operation at room temperature. Due to the photovoltaic operation and virtual increase in the bandoffset, the device presents both low dark current and low noise. The Johnson noise limited specific detectivity reaches values as high as 1.4 × 1011 Jones at 80 K. At 300 K, the detectivity obtained is 7.0 × 105 Jones.

Herein, two challenges are addressed, which quantum well infrared photodetectors (QWIPs), based on III-V semiconductors, face, namely: photodetection within the so-called "forbidden gap", between 1.7 and 2.5 microns, and room temperature operation using thermal sources. First, to reach this forbidden wavelength range, a QWIP which consists of a superlattice structure with a central quantum well (QW) with a different thickness is presented. The different QW in the symmetric structure, which plays the role of a defect in the otherwise periodic structure, gives rise to localized states in the continuum. The proposed InGaAs/InAlAs superlattice QWIP detects radiation around 2.1 microns, beyond the materials bandoffset. Additionally, the wavefunction parity anomaly is explored to increase the oscillator strength of the optical transitions involving higher order states. Second, with the purpose of achieving room temperature operation, an asymmetric InGaAs/InAlAs superlattice, in which the QW with a different thickness is not in the center, is used to detect infrared radiation around 4 microns at 300 K. This structure operates in the photovoltaic mode because it gives rise to states in the continuum which are localized in one direction and extended in the other, leading to a preferential direction for current flow.

We use the leaky electronic state in the continuum concept to create a photovoltaic and photoconductive dual-mode operation superlattice infrared photodetector working at a temperature as high as room temperature. An asymmetric superlattice InGaAs/InAlAs is designed to virtually increase the material band offset and to create a localized state in the continuum with a preferential direction for electron extraction. These two characteristics are responsible for low dark current and high operating temperature of the device. At λp=4.1μm response peak, the highest specific detectivity is 5.7×1010 Jones for +5.0V at 80 K, and at room temperature, it is 1.3×105 Jones for null bias.