Heat Dissipation Schemes in AlInAs/InGaAs/InP Quantum Cascade Lasers Monitored by CCD Thermoreflectance

Abstract

Abstract:In this paper, we report on the experimental investigation of the thermal performance of lattice matched AlInAs/InGaAs/InP quantum cascade lasers. Investigated designs include double trench, single mesa, and buried heterostructures, which were grown by combined Molecular Beam Epitaxy (MBE) and Metal Organic Vapor Phase Epitaxy (MOVPE) techniques. The thermal characteristics of lasers are investigated by Charge-Coupled Device CCD thermoreflectance. This method allows for the fast and accurate registration of high-resolution temperature maps of the whole device. We observe different heat dissipation mechanisms for investigated geometries of Quantum Cascade Lasers (QCLs). From the thermal point of view, the preferred design is the buried heterostructure. The buried heterostructures structure and epi-layer down mounting help dissipate the heat generated from active core of the QCL. The experimental results are in very good agreement with theoretical predictions of heat dissipation in various device constructions.

In-Depth Experimental Analysis of Influence of Electroplated Gold Thickness on Thermal and Electro-Optical Properties of mid-IR AlInAs/InGaAs/InP Quantum Cascade Lasers

“…For a driving current of 1.25 A, an increase of gold layer thickness from 1.5 μm to 5.0 μm results in a 50% reduction of active region temperature. This is roughly the same value as in the case of a buried heterostructure (BH) mounted epi-down design, which is considered the most effective in terms of heat extraction [ 25 ]. However, considering that BH technology requires two-step epitaxy and complicated processing, thick electroplated gold technology seems to be a promising alternative, in particular in the case of cost-effective production technology.…”

“…Direct information about the temperature of the device during pulsed operation can be obtained using the charge-coupled device (CCD)-based thermoreflectance (CCD-TR) [ 24 , 25 ], which allows for both high spatial (0.6 μm) and temperature resolution (below 1 K) imaging of temperature distribution on the laser facet. The optical part of the CCD–TR setup is based on the optical microscope equipped with a 100× long working distance objective.…”

Near‐Field Thermal Profiling and 3D Anisotropic Thermal Analysis of Quantum Cascade Lasers

“…In this work, we report on developing an IR‐SNOM technique with high temperature and spatial resolutions, both achieved by opening a subwavelength aperture at the tip of an IR fiber optic probe. We apply this technique to study the time constants in InP/InAlAs/InGaAs buried heterostructure (BH) mounted epi‐layer side down QCLs––a geometry reported to have the best thermal performance by Pieŕscínska et al [ 22 ] To verify the experimental findings, we develop an anisotropic 3D model to study steady‐state and transient heat transfer in these QCLs. Furthermore, we consider various realistic device structures, such as the laser chip overhanging the submount, with different dielectric coatings placed on the front facet of the active region.…”

“…[21] In this work, we report on developing an IR-SNOM technique with high temperature and spatial resolutions, both achieved by opening a subwavelength aperture at the tip of an IR fiber optic probe. We apply this technique to study the time constants in InP/InAlAs/InGaAs buried heterostructure (BH) mounted epi-layer side down QCLs--a geometry reported to have the best thermal performance by Pieŕscínska et al [22] To verify the experimental findings, we develop an anisotropic 3D model to study steady-state and…”

Optical spectroscopy studies of atom intermixing in the core versus growth temperature of the claddings in MOCVD-grown quantum cascade lasers

“…Another typical approach to reduce costs is to perform combined growth: MBE technique is used to grow the active core of the laser and metal organic chemical vapor deposition (MOCVD) to over-growth the active core with thick cladding layers. The complexity of the combined growth results from growing of the bottom cladding layer at first, transfer of the sample into the MBE reactor in order to deposit the active core, and finally the overgrowth of the active core with upper cladding in a MOCVD machine [14,15]. In such a multi-step fabrication process the cladding's temperature growth is the parameter of Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.…”