Study of gallium-oxide-based ultraviolet photo-detectors

CHERROUN, RIMA (2025) Study of gallium-oxide-based ultraviolet photo-detectors. Doctoral thesis, Université Mohamed Khider (Biskra - Algérie).

Text Cherroun Rima PhD Thesis- Final Version 10-02-2025.pdf Download (7MB)

Abstract

This study presents a numerical simulation of an IZTO/¯-Ga2O3 Schottky barrier ultraviolet photodetector (SB UV-PhD), commonly referred to as a solar-blind UV photodetector, designed to operate specifically at a wavelength of 255 nm. The simulations were performed using SILVACO-ATLAS, a renowned 2D and 3D modeling software. Key parameters investigated include the current density–voltage (J–V) characteristics, responsivity, and internal quantum efficiency (IQE),with an additional focus on detectivity and time-dependent photo response (T-D PhR). The study is organized into two main parts. Initially, efforts were directed towards replicating experimental J–V characteristics under various conditions: in the dark and illuminated with wavelengths of 500 nm, 385 nm, and 255 nm. Notably, the influence of shallow and deep traps, particularly on persistent photoconductivity (PPC), was examined. The most significant impact was observed from the deepest traps (ET Æ 0.74eV and ET Æ 1.04eV ), which contributed to a decay time of 0.05 s. Moreover, incorporating an (Al0.39Ga0.61)2O3 passivation layer on the device’s surface significantly enhanced its performance. In the second part of the study, further optimization was pursued by substituting the ¯-Ga2O3:Sn substrate with 4H-SiC and introducing a buffer layer between the ¯-Ga2O3:Si drift layer and the new substrate. Additionally, the top contact IZTO was replaced with Graphene, considering the effect of work function and electronic affinity. These optimizations yielded enhanced device metrics: a photocurrent density of 7.38×10¡5A/cm2, responsivity of 0.074 A/W, IQE of 0.57, and detectivity of 5×1012 Jones at - 1 V under 255 nm illumination. Furthermore, the device demonstrated robustness at elevated operating temperatures. In summary, this research not only simulated the performance of the IZTO/¯-Ga2O3 SB UV-PhD under specific operating conditions but also explored significant enhancements through material and structural optimizations, thereby improving its overall photodetection capabilities.

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