Doping effects on electrical and dynamical characteristics of GaAs / AlGaAs quantum cascade laser

Erada A Al-Dabbagh,Ragheed M Ibrahim

doi:10.33899/edusj.2008.56103

Abstract

A theoretical analysis of the doping density level influence on the output characteristics of GaAs/Al0.45Ga0.55As triple quantum well QCL emitting at (=9 m) is presented. The employed theoretical model was based on Schrodinger equation analysis. Six different doping density levels, have been used in this study to explain doping density level influence on model gain as a function of wavelength and negative differential resistance (NDR). In the conventionally employed high doping regime, the wavelength shift to the shorter wavelength furthermore to decrease of the peak gain value with doping density level increase has been observed. The available current range before the occurrence of the NDR reduced when the doping density level decrease was found.

Highlights

The idea of electrically pumped intersubband lasers or quantum cascade lasers (QCLs) as unipolar semiconductor devices utilizing intersubband transitions in a repetition of identical coupled multiquantum-well structures was pioneered by Kazarinov and Suris.[1]
We have reported a detailed study of the impact of doping densities on the performance of GaAs/Al0.45Ga0.55As mid-infrared 3 QW-based quantum cascade laser emitting at ∼ 9μm
The theoretical model is based on Schrodinger equation analysis

Summary

1- Introduction

The idea of electrically pumped intersubband lasers or quantum cascade lasers (QCLs) as unipolar semiconductor devices utilizing intersubband transitions in a repetition of identical coupled multiquantum-well structures was pioneered by Kazarinov and Suris.[1]. Laser operation has been reported on other material systems, i.e., AlGaAs on a GaAs substrate[7] and Al(Ga)Sb on InAs.[8] Devices with Sb-containing barriers on both InAs substrate[9] as well as on InP substrate[10] are promising for either increasing the electron confinement or reducing the emission wavelength, and above room temperature pulsed operation on both substrates were recently reported.[9]. The doping level in the active region is an important parameter with particular influence on the dynamical working range of QCLs. Until now, very few experimental investigations have been presented including the influence of the injector doping of InP-based[15] and GaAs- based[16] QCL threshold current. We report such an investigation of GaAs/Al0.45Ga0.55As triple quantum well QCL emitting at (λ=9 μm) design[17] in which the influence of the doping density on the carrier dynamics and electrical characteristics are analyzed. Tunneling through to E2 (2) in the second quantum well W2 it makes a vertical transition to E2(1), after which rapidly tunnels to E3 in the third quantum well W3 and escapes out of the structure

Well gain stage

5- Conclusions