DESIGN AND CHARACTERIZATION OF HIGH PERFORMANCE EXTENDED SHORT-WAVELENGTH INFRARED PHOTODETECTORS WITH BACKSIDE REFLECTOR

Date

2025-1-7

Author

Satılmış, Mert

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This thesis examines the growth, fabrication, and performance optimization of InAsP/InGaAs E-SWIR photodiodes with a 2.55 µm cut-off wavelength. It consolidates insights from books, articles, and theses, serving as a valuable reference for researchers and engineers in infrared detection. The thesis explores the principles of light and its detection mechanisms before concentrating on the development of a photodetector for the E-SWIR band. The widely used E-SWIR detector structure is based on InGaAs absorbers due to their well-established growth techniques and ease of fabrication. Extending the wavelength range requires increasing the In mole fraction from 53% to 80%, causing up to 2% lattice mismatch with the InP substrate. This mismatch elevates G-R current and trap levels, increasing dark current and reducing detector performance. Improved fabrication techniques can mitigate these issues.This thesis begins with the characterization of wet etching fabrication and explores methods to reduce surface-related dark current. It focuses on depositing SiNx:H via the ICPCVD method, varying NH3/SiH4 ratios while maintaining constant pressure, power, and Ar gas flow. FTIR measurements reveal proportional changes in N-H, Si H, and Si-N bond numbers with H content, showing that K- trap center density depends on NH3/SiH4 ratios. Additionally, light trapping techniques are implemented to enhance device responsivity. Front-illuminated devices are coated with backside Ti/Au reflectors, improving both responsivity and fabrication yield.

Subject Keywords

extended SWIR, InAsP/InGaAs, SiNx:H, Dangling bonds, Light Trapping

URI

https://hdl.handle.net/11511/113056

Collections

Graduate School of Natural and Applied Sciences, Thesis