The role of excitons and trions on electron spin polarization in quantum wells

TL;DR

This study investigates how excitons and trions influence electron spin polarization in quantum wells, revealing that free electron excitation and doping levels significantly affect spin polarization dynamics.

Contribution

It provides a detailed dynamic analysis of spin polarization evolution considering excitons, trions, and doping effects using matrix density formalism.

Findings

Photoexcitation of free electrons yields higher spin polarization

Increasing excitation energy enhances spin polarization

Lower doping concentrations lead to increased spin polarization

Abstract

We have studied the time evolution of the electron spin polarization under continuous photoexcitation in remotely n-doped semiconductor quantum wells. The doped region allows us to get the necessary excess of free electrons to form trions. We have considered electron resonant photoexcitation at free, exciton and trion electron energy levels. Also, we have studied the relative effect of photoexcitation energy density and doping concentration. In order to obtain the two-dimensional density evolution of the different species, we have performed dynamic calculations through the matrix density formalism. Our results indicate that photoexcitation of free electron level leads to a higher spin polarization. Also, we have found that increasing the photoexcitation energy or diminishing the doping enhances spin polarization.