ZnO/AlN Clad Waveguides for AlGaN-Based Quantum Cascade Lasers

Abstract

Waveguide designs for AlGaN-based near-infrared quantum cascade lasers are proposed and analyzed using optical mode solvers. Because of the poor electrical conductivity, AlN is not a suitable cladding material for the AlN/GaN/AlGaN gain region. Instead we propose the use of ZnO as a conductive top cladding and to embed the gain region between AlGaN current injection and extraction regions so that an AlN substrate can be used as the lower cladding. We also examine the use of an AlN template on a SiC substrate and find that it can also provide sufficient mode confinement with negligible radiation loss into the SiC substrate. We identify a single mode ridge waveguide design with reasonable mode confinement (40%) and loss (39 cm −1).

Optoelectronic properties of doped hydrothermal ZnO thin films

“…Due to its wide band gap and ease of achieving n‐type conductivity, ZnO thin films can simultaneously achieve high optical transparency and low electrical resistivity. Transparent electrodes composed of ZnO have been shown to be applicable to optoelectronic devices such as light emitting diodes (LEDs) , laser diodes , and photovoltaics . For example, hydrothermally deposited ZnO thin films have been shown to outperform both thin Ni/Au Sb‐doped indium oxide (ITO) as current spreading transparent electrodes for InGaN‐based LEDs.…”