Characteristics of II–VI Quantum Dot Infrared Photo-Detectors

Abstract

We theoretically investigate the performance of a II-VI ZnCdSe/ZnSebased quantum dot infrared photodetector (QDIP) utilizing intersubband hole transitions in the valence band of the QDs to absorb infrared radiation. The analysis starts with the computation of band structure via multi-band effective mass model based on the Luttinger-Kohn Hamiltonian with the inclusion of strain effects. The theoretical formulation is further used to determine the spectral responsivity and dark current characteristics of the QDIP. IntroductionInfrared detectors are required in the various imaging applications, including medical diagnostics, astronomy, remote sensing, space-based surveillance, and thermal imaging [1]. Initially, infrared detectors were developed using narrow band gap semiconductors such as HgCdTe and InSb [2], which make use of interband transitions to detect the infrared radiation. Operating wavelength of these detectors can be modified by controlling the band gap of the semiconductor material via changing the alloys composition. However, the processing of narrow gap semiconductors creates problem in the epitaxial growth, non-uniformity, low yield and high cost [3]. Alternatively, intersubband transitions in the quantum hetero-structures have been utilized to detect the infrared radiation. The attractive feature of intersubband transition based detectors is that they do not require narrow band gap semiconductors. This provides flexibility to use any available wide band gap material to fabricate infrared detector. Moreover, quantum hetero-structure