Energy level structure and electron relaxation times in InAs∕InxGa1−xAs quantum dot-in-a-well structures

Abstract

Complementary interband and intraband optical spectroscopic techniques are used to investigate the band structure and carrier relaxation times in technologically important InAs∕InGaAs∕GaAs quantum dot-in-a-well (DWELL) structures. We determine the dot ground to first excited state energies to be 42meV in the conduction band and 18meV in the valence band. Using intraband pump-probe experiments, electron relaxation times from the well states to the dot ground state are measured to be ∼5ps at 10K. Our results provide important parameters for the design and simulation of DWELL-based interband lasers and intraband midinfrared photodetectors.

Optical pumping as artificial doping in quantum dots-in-a-well infrared photodetectors

“…6 Several groups have even reported response in the far infrared region ͑Ͼ20 m͒ emanating from transitions between different bound QD states. 7,8 However, a detailed understanding of all relevant transitions occurring in the detector has not yet been achieved. This knowledge is essential in order to design and optimize a high performance infrared detector.…”

High temperature operation of quantum dots-in-a-well infrared photodetectors

“…The dots-in-a-well (DWELL) design [8][9][10][11][12][13], in which InAs quantum dots are placed in an InGaAs-GaAs or an InGaAs-GaAs-AlGaAs quantum well, effectively solves this problem and allows precise control of the peak wavelength by simply changing the width of the quantum well. The infrared absorption is a result of intersubband transitions from quantum dot ground state to quantum well bound state or the continuum [9,14].…”

Review of current progress in quantum dot infrared photodetectors

“…In our research group, we have designed photodetectors with a quantum dots-in-a-well (DWELL) design [44][45][46] which allows superior control of peak wavelength of operation, improves optical properties of the quantum dots and reduces dark currents [34,[47][48][49][50][51][52]. Schematics of a typical DWELL photodetector are shown in Fig.…”