Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching

Abstract

Films of nanocrystalline silicon (nc-Si) were prepared from hydrogenated amorphous silicon (a-Si:H) by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics.

Comparative Study of Furnace and Flash Lamp Annealed Silicon Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

“…crystalline silicon was a clear indication of the films being crystallized, which has been reported in previous works [21,22]. Figure 3 shows the reflectance spectra for the as-deposited, furnace annealed at 650 °C and flash lamp annealed samples, respectively.…”

“…The top layer-2 was treated as a Bruggeman's EMA for poly-Si and void mixture, where poly-Si was fitted using Tauc-Lorentz and Gasussian oscillators. The optical model resulted an excellent fit to the experimental psi and delta curve obtained from SE measurements as can be seen crystalline silicon was a clear indication of the films being crystallized, which has been reported in previous works [21,22]. Figure 3 shows the reflectance spectra for the as-deposited, furnace annealed at 650 °C and flash lamp annealed samples, respectively.…”

“…A direct evidence of crystallization of the a-Si films was that a new characteristic peak around 280 nm in the UV region of the reflectance spectra appeared for the films annealed at temperatures above 550 • C. The characteristic peak around~280 nm represents reflection band, which can be explained by the optical transitions near the direct band gap [20]. This characteristic peak of crystalline silicon was a clear indication of the films being crystallized, which has been reported in previous works [21,22].…”

Темплатный Синтез Монодисперсных Сферических Нанопористых Частиц Кремния Субмикронного Размера

“…4). Максимум данной полосы, соответствующей TO моде Si, смещается в высокочастотную область спектра с 491 см −1 (кривая 1) до 519 см −1 (кривая 4), что свидетельствует об увеличении размеров кристаллитов Si [35][36][37][38]. В спектре фотолюминесценции частиц np-Si присутствуют широкие полосы в видимом и ближнем ИК спектральных диапазонах (рис.…”

“…В спектре фотолюминесценции частиц np-Si присутствуют широкие полосы в видимом и ближнем ИК спектральных диапазонах (рис. 5), наблюдавшиеся ранее в спектрах ФЛ нанокристаллического Si [37,[39][40][41][42]. После лазерного отжига мощностью P exc = 5−10 кВт/см 2 в течение 1 мин интенсивность ФЛ возрастает в 2−3 раза.…”