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Research And Utilization Of Polarization Effects In GaN Based LED

Posted on:2010-02-03Degree:MasterType:Thesis
Country:ChinaCandidate:Q H ZhengFull Text:PDF
GTID:2178360275494502Subject:Condensed matter physics
Abstract/Summary:PDF Full Text Request
Based on the polarization effect inⅢ-Ⅴnitride, we solve self-consistently the Schr(o|¨)dinger and Poisson equation. Both utilization and elimination of the polarization field are proposed. Experimentally, specific contact resistance to p-GaN is reduced and internal quantum efficiency of LED is improved. The main work we have done are listed as follows,1. Solving self-consistently the Schr(o|¨)dinger and Poisson equation under the influence of polarization fields via computer simulation. Eigenfunction of the electron and hole and their corresponding eigenvalues are investigated. The simulation can be generalized to solve the time-independent Schrodinger equations with arbitrary potentials.2. As polarization field lead to oscillation of the valence band edges, result in enhancement of Mg ionization and improvement of hole concentration, InGaN/AlGaN superlattice strained-layers (SLS) is introduced as a cladding layer for GaN based LED. The SLS can reduce specific contact resistance and served as a current spreading layer. The band structure, ionization of Mg and averaged hole concentration of InGaN/AlGaN, InGaN/GaN and AlGaN/GaN SLS are compared at the same Mg doping level. The Optimal Mg doping level is also given. Experimentally, lower specific contact resistance to p-GaN is realized.3. To overcome the separation of electron and hole due to the polarization filed, In composition modulated LED is proposed. It can counteract part of the polarization and improve the recombine rate of electron and hole. The IQE of the LED is measured by variable temperatures PL.This dissertation presents the utilization and elimination of the polarization field in GaN based LED, the main innovation of this paper is that we use InGaN/AlGaN SLS to obtain relative higher hole concentration, and use gradual changed In composition to get to get a better band structure for LED.
Keywords/Search Tags:polarization effect, superlattice, Internal quantum efficiency
PDF Full Text Request
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