Study of CuInS2 thin film’s application to near-infrared photodetectors

Abstract

In this dissertation CuInS2 (CIS) thin films as the absorption layer of a near infrared photodetector (PD) is studied CIS thin film has high optical absorption coefficient and high solar energy conversion efficiency and its bandgap is within the NIR spectrum Therefore it is a good NIR PD candidate as the absorber layer In this study formation of CIS film was prepared by co-sputtering Cu/In thin films on a Mo coated substrate followed by appropriate sulfurization Deposition of Al film and photolithography processes were used to pattern the electrodes of the metal-semiconductor-metal (MSM) PDs In this study the influence of precursor Cu/In ratio on CIS thin film as well as was on device performance is investigated Scanning electron microscope was used to observe the film’s morphology crystalline phase and orientation were determined by X-ray diffraction patterns and Raman analysis and an energy-dispersive X-ray spectroscopy was used to analyze the compositions of the films Photoluminescence measurements were to used for investigating CIS film’s quality and its possible bandgap Current-voltage characteristics under or without NIR illumination was to characterize the PDs that fabricated Precursors of different Cu/In ratios controlled by adjusting co-sputtering powers were sulfurized as the atomic ratio of Cu/In increases (0 78-1 22 range) its crystallinity of the CIS film improves The best PD sample that fabricated exhibits a one-order of magnitude in photocurrent amplification with 2-?m electrode spacing More sensitive amplification can be expected by using other CIS forming methods such as molecular beam epitaxy

Date of Award	2015 Jul 8
Original language	English
Supervisor	Dung-Ching Perng (Supervisor)