Modeling and analysis of intraband absorption in quantum-dot-in-well mid-infrared photodetectors

Abstract

Intraband absorption in quantum-dot-in-a-well (DWELL) mid-infrared photodetectors is investigated using photocurrent spectroscopy and computationally cost-effective modeling linked to experimental data. The DWELL systems are challenging for modeling the electronic structure, which involves both discrete levels and the continuum energy spectrum. We show that the latter can be successfully approximated by a quasi-continuum in a large three-dimensional (3D) “quantum box” in which the electronic structure is calculated in the effective mass approximation using the finite element method. Experimental and simulated spectra show good agreement with each other, which justifies using the modeling for analysis of the experimental data. In particular, the origin of the peaks and the dot parameters, such as composition are deduced. Effects of dot composition and shape on the intraband absorption spectra are also predicted. Our model proves to be a useful tool in designing and analyzing advanced DWELL structures for any realistic 3D quantum dot geometry.

Intraband carrier dynamics in InAs/GaAs quantum dots stimulated by bound-to-continuum excitation

“…The intraband absorption spectrum of QDs has been calculated by effective mass approximation. [9][10][11][12] Recently, Luque et al reported that the intraband absorption coefficient for both the bound-to-bound and bound-to-continuum transitions is comparable to the interband absorption coefficient in QDs. 12 On the other hand, the intraband absorption in InAs/ GaAs QDs has been measured by photoinduced absorption spectroscopy 13,14 and time-resolved photoluminescence (PL) quenching measurements.…”

The structural parameters of self-assembled quantum dots determined from the optical spectra

“…More modeling formalism details are available in Ref. [4]. Photoluminescence (PL) spectra were measured at 10 K and 300 K using an Ar+-ion laser and a liquid-nitrogen cooled Ge detector.…”

Microscopic model for intersubband gain from electrically pumped quantum-dot structures

“…33 QD intersubband transitions are particularly promising for mid-infrared wavelengths. 34 These transitions allow light emission normal to the growth direction. Additionally, they are a basic requirement for the realization of a QCL consisting of QDs.…”