الفهرس 
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Abstract
This thesis focuses on the exploration of nanowire detectors, which have gained significant attention due to their advantageous features such as high resolution and gain. Nanowires have emerged as an innovative technology for X-ray detection, revolutionizing the field with their unique properties and capabilities.
Our focus is on designing and optimizing nanowire detectors for X-ray detection based on Indium Phosphide (InP) material. First, a physical based model for a p-i-n photodiode is developed. This model is based on solving the main semiconductor equations to provide simple analytical equations. The model is validated against measurements, achieving high accuracy. In addition, SILVACO TCAD tools have been involved to benchmark all parameters and physical models in order to ensure practical evidence at different conditions such as energies and biasing. The model can predict the current that is produced from the incident X-ray beam at different energies. The effect of trap charges, biasing, doping concentration and flux density are considered in the model. MATLAB is used to implement the proposed model. Good agreement is obtained when comparing the output results from the model against SILVACO TCAD simulation and experimental results for various beam energies and conditions. Also, the efficiency of the photodiode under investigation is obtained at different energies and bias voltages. The efficiency of the photodiode is found to be about 78 to 55 when photon flux is changed from 2×109 to 6.2 ×107 (Ph./s) at 0.2 V biasing, respectively.
Moreover, within this thesis, the investigation delves into electrical characteristics of a suggested NW X-ray detector operating as a photoconductor having an n+-n-n+ configuration. The aim of this part is to enhance the detector’s performance under different conditions such as flux density, biasing voltage, NW diameter, active region length and temperature. The simulation results predict the current produced by incident X-ray beams and the gain, while taking into account the relationship between the diameter and energy gap of InP NWs. The study also models a single NW and considers the effects of trapping charges and photodoping on the behavior of the NW. Additionally, pyPENELOPE is used to simulate the charge distribution in the InP NW material. This charge distribution is found to be compatible with the TCAD simulation results, which further confirms our simulation accuracy.
In addition, InP-based NW phototransistor is investigated through developing a physically based model. The model is based on solving the basic semiconductor equations for bipolar transistors and considering the effects of charge distribution on the bulk and on the surface. The developed model also takes into consideration the impact of surface traps, which are induced by photogenerated carriers situated at the surface of the nanowire. Further, photogating phenomena and photodoping are also included. The displacement damage (DD) is also investigated; an issue arises when the detector is exposed to repeated doses. The presented analytical model can predict the current produced from the incident X-ray beam at various energies. The calculation of the gain of the presented nanowire carefully considers the different governing effects at several values of energies as well as biasing voltage and doping. The proposed model is built in MATLAB, and the validity check of the model results is achieved using SILVACO TCAD device simulation. Comparisons between the proposed model results and SILVACO TCAD device simulation are provided and show good agreement.