The operation of multiquantum-well barriers

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dc.contributor.advisor Lambkin, John D.
dc.contributor.advisor van der Poel, Carel J. Morrison, Alan P. 2012-11-26T17:33:38Z 2012-11-26T17:33:38Z 1996-12 1996
dc.identifier.citation Morrison, A. P. 1996. The operation of multiquantum-well barriers. PhD Thesis, University College Cork. en
dc.description.abstract The multiquantum barrier (MQB), proposed by Iga et al in 1986, has been shown by several researchers to be an effective structure for improving the operating characteristics of laser diodes. These improvements include a reduction in the laser threshold current and increased characteristic temperatures. The operation of the MQB has been described as providing an increased barrier to electron overflow by reflecting high energy electrons trying to escape from the active region of the laser.This is achieved in a manner analogous to a Bragg reflector in optics. This thesis presents an investigation of the effectiveness of the MQB as an electron reflector. Numerical models have been developed for calculating the electron reflection due to MQB. Novel optical and electrical characterisation techniques have been used to try to measure an increase in barrier height due to the MQB in AlGaInP.It has been shown that the inclusion of MQB structures in bulk double heterostructure visible laser diodes can halve the threshold current above room temperature and the characteristic temperature of these lasers can be increased by up to 20K.These improvements are shown to occur in visible laser diodes even with the inclusion of theoretically ineffective MQB structures, hence the observed improvement in the characteristics of the laser diodes described above cannot be uniquely attributed to an increased barrier height due to enhance electron reflection. It is proposed here that the MQB improves the performance of laser diodes by proventing the diffusion of zinc into the active region of the laser. It is also proposed that the trapped zinc in the MQB region of the laser diode locally increases the p-type doping bringing the quasi-Fermi level for holes closer to the valence band edge thus increasing the barrier to electron overflow in the conduction band. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 1996, Alan P. Morrison en
dc.rights.uri en
dc.subject Multiquantum barrier (MQB) en
dc.subject Laser diodes en
dc.subject.lcsh Lasers en
dc.title The operation of multiquantum-well barriers en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD (Engineering) en
dc.internal.availability Full text available en
dc.description.version Accepted Version en
dc.description.status Not peer reviewed en Tyndall National Institute en

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© 1996, Alan P. Morrison Except where otherwise noted, this item's license is described as © 1996, Alan P. Morrison
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