PL and EL Studies of Dysprosium and Holmium Doped Silicon Based on Dislocation Engineering Method
Creators: name: MUSTAFA, ZULHILMI
Publisher: name: University of Surrey
Year: 2021

description: "The concept of light emission from silicon had been an obsession among scientists since the 1960s. The concept had received much research attention from scientists all over the world. Since then, many studies had attempted to examine the idea of implanting silicon with other materials to produce light. The studies suggested several approaches such as integration of III-V materials on Si, Si nano-crystallization, SiGe superlattice strain engineering and dislocation engineering.
description: Dislocation engineering is seen as one of the more promising approaches. Dislocation engineering involves the process of doping with boron ions to introduce dislocation loops and incorporation of optically active centres for extended optical wavelengths. Previous researches had examined the implantation of rare earth elements namely, erbium, thulium, europium, ytterbium, cerium, praseodymium with encouraging results. Two other rare earth elements that need further examination are dysprosium (Dy) and holmium (Ho).
description: Photoluminescence and electroluminescence studies are performed on Dy and Ho that were implanted into Si DELED. For Dy, the results obtained are the two main emission regions that can be observed between 1250–1450 nm and 1650–1900 nm. There are sixteen sharp emission lines between 1250–1450 nm and seven sharp emission lines between 1650–1900 nm regions. The brightest Dy emissions are observed at 1345 nm with peak linewidth of 10 nm and 1736 nm with peak linewidth of 5 nm respectively when post-annealed at 850°C for 5 minutes. The Dy emission can be attributed to its internal transitions between the second Dy excited state, 6H11/2, and the ground state, 6H15/2 manifold, and between the third Dy excited state that is an overlapping of two manifolds, 6H9/2 + 6F11/2, and the ground state, 6H15/2. For Ho, the results showed four main emission lines in the range of the 1900-2100 nm region. The strongest Ho emission is observed at 1964.5 nm with peak linewidth of 20 nm when post-annealed at 775°C for 40 seconds. The Ho emission can be attributed to its internal transitions between the first Ho excited state, 5I7, and the ground state, 5I8.
description: The emission wavelengths observed in Dy and Ho implanted into Si DELED are within the required fibre optical communication bands between 1 µm and 2 µm. The results of this research are comparable with emission wavelengths of other rare earth elements implanted into Si DELED. The Dy emission lines observed are similar with the study on GaAs host material. The line peak positions observed in the spectra are closely matched with slight variation in the line peak position. The slight line peak position variations can be due to the difference in the measurement temperature and the different crystal fields of the hosts. The emission lines observed for Ho are also comparable with emission lines of other studies on the same Si host material. Emission lines obtained from this study showed that the dislocation engineering approach gives greater emission intensity. Both Dy and Ho observe conventional rare earth behaviour as reported from similar researches. In summary, Dy and Ho implanted into silicon are capable to emit light technologically important wavelengths. However, further research is required before they can be put into commercial applications."