Infrared electroluminescence from erbium-doped spark-processed silicon

• Published in: Journal of luminescence 2007-12, Vol.127 (2), p.339-348
• Main Authors: Kim, Kwanghoon, Hummel, Rolf E.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electroluminescence; Erbium; Exact sciences and technology; Infrared; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other luminescence and radiative recombination; Physics; Silicon; Spark-processing
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2006.12.009

The infrared (IR) electroluminescence (EL) of erbium-doped spark-processed silicon (sp-Si) was investigated. For this, a device was constructed which consisted of a silicon wafer on which an erbium layer was vapor deposited, followed by spark-processing and rapid thermal annealing for 15 min at 900 °C in air. The metallization consisted of a 200 nm Ag layer (above the spark-processed area) and a 50 nm thick Al film (on the “back side”), containing a window through which the light could escape. Maximal light emission occurred near 1.55 μm, that is, at a wavelength where commonly used fiber optical materials have their minimum in energy loss. The processing parameters for most efficient light emission were an Er thickness of 200–300 nm, a spark-processing time of about 30 s, an n-type Si wafer having a low (3–5 Ω cm) resistivity, an operating temperature near room temperature, and an operating voltage between 25 and 40 V under reverse bias. The results are interpreted by postulating an energy transfer from sp-Si to the Er 3+ ions involving the first excited state 4I 13/2 to ground state 4I 15/2. Further, impact excitation and hot electrons that are accelerated into the erbium doped sp-Si by the applied field (100 kV/cm) are considered.