Effects of Non parabolic Bands on Nanostructure Laser Devices

摘要

Most material systems have parabolic band structures at the band edge, however away from the band edge the bands arestrongly non parabolic. Other material systems are strongly parabolic at the band edge such as IV-VI lead saltsemiconductors. The effects of this property can be ignored for bulk material and structures. However, we will show thatits effect can't be ignored in the nanoscale range and it is important to calculate for and take into consideration theeffects of this unique property in any design and analysis. Based on the energy dependent effective mass, a theoreticalmodel was developed to conduct this study on several lead salt (IV-VI) laser nanostructures in the infrared region. Theeffects of non-parabolicity on the gain versus current density relation are a reduction in the current density needed forany given gain and an increase in the gain saturation level. The non-parabolicity of the bands in the growth directionlowers the values of the confinement factor relative to parabolic bands which in turn lowers the modal gain values.Finally, the effects of non-parabolicity on the threshold current are significant for short cavity lasers and decrease withan increase in the cavity length.