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Title:Strain-controlled impurity-induced disordering for apertures in single-mode vertical-cavity surface-emitting lasers
Author(s):Su, Patrick
Advisor(s):Dallesasse, John M.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):impurity-induced disordering, vertical-cavity surface-emitting lasers, mode-control
Abstract:Vertical-Cavity Surface-Emitting Lasers (VCSELs) have become ubiquitous in modern consumer markets. Owing to their small footprint, circular-beam profile, on-wafer probing capability, and high reliability, VCSELs have been widely deployed for data communication transmitters and position sensors. In the advent of emerging applications such as autonomous driving and 3-D facial recognition systems, high-power 2D VCSEL arrays are being used as the premier illumination device for time-of-flight (ToF)-based light detection and ranging (LIDAR) optical sensors. Through the initiation of Zn diffusion, impurity-induced disordering (IID) has been demonstrated to enable optical mode control, increased modulation frequencies, and provide carrier and photon confinement in vertical-cavity surface-emitting lasers. While disordering provides a wafer-scale method of improving device performance, the regions of disordering must be carefully controlled. Adverse effects can overshadow the benefits of disordering if it is not properly managed. Due to the isotropic nature of diffusion, undesirable lateral undercutting can occur during deep disordering processes where the severity of this effect is defined by the initial diffusion front formed. In this work, the fine control of Zn diffusion fronts in apertures formed using impurity-induced disordering is presented. By tailoring the diffusion mask strain, the diffusion front curvature of the impurity-induced disordering aperture can be controlled. Through modifying the composition of SiN$_{x}$ diffusion masks, various film stresses can be achieved. When employed for disordering, these form a variety of disordering apertures with differing diffusion fronts. These distinct impurity-induced disordering apertures are characterized for their lateral-to-vertical diffusion front ratios and an analysis and discussion of the physical mechanisms is presented The demonstration of this work enables more sophisticated and precise disorder-defined apertures for high-performance VCSELs.
Issue Date:2019-04-25
Rights Information:© 2019 Patrick Su
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05

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