Direct Numerical Simulation of Exciton Formation in GaAs Quantum Wells: Effects of Confinement, Donor Impurities and External Magnetic Field

Simulación Numérica Directa de la Formación de Excitones en Pozos Cuánticos de GaAs: Efectos del Confinamiento, Impurezas Donadoras y Campo Magnético Externo

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Fabian Andres Castaño Usuga
Alvaro Luis Morales
Carlos Alberto Duque

Resumen

We present a numerical study of excitonic states in GaAs quantum wells embedded in Al0.3Ga0.7As barriers, focusing on the effects of quantum confinement and donor impurities. Using a finite element method in cylindrical coordinates, we solve the time-independent Schrödinger equation to obtain electron and hole wavefunctions without assuming trial forms. A parametric sweep of the well thickness from 0.1 nm to 20 nm is conducted to analyze confinement-dependent behavior. The exciton binding energy is computed from the Coulomb interaction integral between spatially resolved wavefunctions. Our results show that confinement enhances energy quantization and modulates excitonic coupling, while the presence of a donor impurity significantly increases wavefunction localization and binding energy. Compared to variational approaches, our method offers higher accuracy and greater flexibility for modeling realistic structures, including impurities and complex boundary conditions. This framework provides detailed insight into exciton formation mechanisms and can be extended to model external fields, strain effects, or more complex heterostructures, offering a valuable tool for the design of next-generation optoelectronic and quantum devices.

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