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Title: Near-infrared free carrier absorption in heavily doped silicon

Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10{sup 18} and 3 × 10{sup 20} cm{sup −3}. Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis.
Authors:
 [1] ;  [2] ;  [3] ; ; ;  [1]
  1. School of Engineering, Australian National University, Canberra, ACT 0200 (Australia)
  2. (Australia)
  3. PV Lighthouse, Coledale, NSW 2515 (Australia)
Publication Date:
OSTI Identifier:
22314587
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; BORON; CARRIERS; DENSITY; DIFFUSION; DISPERSIONS; DOPED MATERIALS; EQUIPMENT; PHOSPHORUS; PHOTONS; SILICON; WAVELENGTHS