## Citation

Ooi, Wesley Tat Lung (2020)*Optimisation of Mean Multiplication Gain and Excess Noise Factor in A1xGa1-xN Ultraviolet Avalanche Photodiodes.*Masters thesis, Multimedia University. Full text not available from this repository.

## Abstract

The Monte Carlo (MC) simulation on Gallium Nitride (GaN) and Aluminium Gallium Nitride (AlxGa1-xN, where x = 0.3, 0.45, 0.7) are presented. This work aims to study the AlxGa1-xN avalanche photodiodes (APDs) and optimise the AlxGa1-xN APDs. AlxGa1-xN development has been hampered by the difficulty in growing high quality AlxGa1-xN layer due to high lattice defect which necessitates the MC simulation. The scattering mechanisms such as polar optical phonon scattering, nonpolar optical phonon scattering, acoustic phonon scattering and impurity scattering are simulated which in turn allows the simulation of the carrier transport properties such as drift velocity, energy and free flight of the carriers. The impact ionisation parameters are deduced by the simulation of the ionisation rates and coefficients which is used in the simulation of mean multiplication gain and excess noise factor of AlxGa1-xN APDs by employing random ionisation path length theory. GaN has electron dominate the impact ionisation at high electric field, above 4.04 MV/cm while hole dominate at lower electric field. For Al0.3Ga0.7N and Al0.45Ga0.55N, hole dominates the impact ionisation while electron dominates the impact ionisation for Al0.7Ga0.3N. The mean multiplication gain for GaN APD has electron-initiated multiplication leading at multiplication width, w ≤ 0.2 μm while hole leads the mean multiplication gain at w ≥ 0.26 μm. Hole is leading the multiplication gain at all w for Al0.3Ga0.7N and Al0.45Ga0.55N APDs while electron leads for Al0.7Ga0.3N APDs. The excess noise factor for electron-initiated multiplication of GaN APD is lower compared to hole-initiated at w ≤ 0.2 μm but at w ≥ 0.26 μm, electron produces more excess noise than hole. Hole-initiated multiplication for Al0.3Ga0.7N and Al0.45Ga0.55N APDs have much lower excess noise compared to electron-initiated multiplication at all w while for Al0.7Ga0.3N APDs, electron-initiated multiplication produces lower noise instead. Thereafter, a comparison is made on the four simulated APDs impact ionisation coefficient, breakdown voltage and excess noise factor where it is found that Al0.45Ga0.55N is the best candidate for UV-APD due to the low hole-initiated excess noise factor with moderate breakdown voltage.

Item Type: | Thesis (Masters) |
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Additional Information: | Call No: TK8312 .O55 2020 |

Uncontrolled Keywords: | Avalanche photodiodes |

Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101-6720 Telecommunication. Including telegraphy, telephone, radio, radar, television |

Divisions: | Faculty of Engineering and Technology (FET) |

Depositing User: | Ms Nurul Iqtiani Ahmad |

Date Deposited: | 24 Feb 2023 04:18 |

Last Modified: | 24 Feb 2023 04:18 |

URII: | http://shdl.mmu.edu.my/id/eprint/11147 |

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