Design And Optimization Of Multi--Quantum \\Tells For Gaas Based Vertical Cavity Surf Ace Emitting Lasers

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dc.contributor.authorJasim, Farah Z
dc.date.accessioned2017-02-16T06:34:27Z
dc.date.available2017-02-16T06:34:27Z
dc.date.issued2011-01
dc.description.abstractDevice simulations for the electrical and optical characteristics of GaAs based vertical cavity surface emitting lasers (VCSELs) have been investigated. In such lasers, carrier's leakage and lateral current separation are some of the major problems in VCSEL design. Thus, in this work the design of VCSEL structures including multi quantum wells (MQWs) active region are described and investigated by Integrated System Engineering Technology Computer Aided Design (ISETCAD) device simulator. The parameters of VCSEL structures are varied and optimized for high performance. This optimization study involves aspects such as the number of distributed Bragg reflectors (DBRs) pairs, thickness of quantum wells, wells number, doping of the DBR pairs, thermal characteristics and several approaches to improve and achieve high efficiency, low threshold current and high output power. In order to enhance the device performance and reduce carrier leakage in~ide the VCSEL cavity, a new model is proposed where three pairs of both p and n-type DBRs nearest to the active region, and which are in the proximity of the spacer are doped at 5xl0+17cm-3 and the rest are doped highly at IxlOt-19 cm-3 concentration. In this case, better matching of carrier distribution of the DBRs and the spacers can be achieved. An output power of 12.7 mW, threshold current of 280 J.lA, and the outer voltage of 2.5 V were obtained from cylindrical structure with radius of 2 Jlm. The output slope efficiency and differential quantum efficiency (DQE) are the key performance parameters of the VCSEL. Slope efficiency of 0. 999 and DQE up to 0.683 at an emission wavelength of 848.30 nm are achieved. This is essentially a very important aspect to be considered for the device fabrication. Large area of VCSELs designs result in multimode operation. A new design is proposed to enhance single fundamental mode with low threshold current operation at higher output with two oxide confined (OC) apertures VCSEL. It was observed that when two apertures with radius of 4.2 11m were added to the node position of the resonator standing wave, single fundamental mode was achieved as well as the threshold current was decreased from 1. 77 to 1.67 mA.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/3738
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectGaAs based vertical cavity surfaceen_US
dc.subjectemitting lasers.en_US
dc.titleDesign And Optimization Of Multi--Quantum \\Tells For Gaas Based Vertical Cavity Surf Ace Emitting Lasersen_US
dc.typeThesisen_US
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