Investigation of in-plane- and z-polarized intersubband transitions in pyramid-shaped InAs/GaAs quantum dots coupled to wetting layer: Size and shape matter

Abstract

In this work, the effects of the shape and size on the intersubband electronic and optical properties of three-dimensional self-assembled pyramid-shaped InAs/GaAs quantum dots (QDs) were investigated in detail. More precisely, in-plane- and z-polarized transitions dipole moment (TDM), oscillator strength (OS), and absorption coefficients of P-to-S, WL-to-P, and WL-to-S transitions were studied as a function of the QD height. The P-to-S TDM showed to be strong and purely in-plane-polarized transition dominating two others. However, the TDMs and OSs of WL-to-P and WL-to-S transitions which are in-plane- and z-polarized transitions, respectively, showed a competition behavior for short and tall QDs. The former dominates for short QDs, and the latter for tall QDs. The physical reasons behind these interesting phenomena were also explained using the probability of finding the carriers in the pyramid region attached to the WL. The theoretical results are in good agreement with experimental data reported for short QDs [Appl. Phys. Lett. 82, 630 (2003)].

A Protocol for Spectroscopists to Isolate The Effect of Berry Geometric Magnetic Forces on Molecular Dynamics

“…where α L is the focus area. Given that the transition dipole moment of the above candidates ranges from µ ≈ 4.5 Debye (Bchl molecules [70,71]) to µ ≈ 1000 Debye (colloidal QD [72]) and assuming that the laser focus area is 0.003 mm 2 (with a beam waist radius of 30 µm), we can then estimate the necessary laser power that one would need to see a reasonable Berry force effect as somewhere between 1.0 and 10 4 Watts (see Table II).…”

Bound to continuum intersubband transition optical properties in the strain reducing layer-assisted InAs quantum dot structure

“…According to the theoretical and experimental reports, the ground state (S) to WL state transition in InAs/GaAs is strongly z-direction polarized [26]. The z-polarized intersubband transition is practically of great importance, because it provides the escaping of carrier to continuum (WL) states which are the basic requirements of QDIR photodetector devices structure [27][28][29].…”