Infrared spectroscopy of silicon for applications in astronomy

TL;DR

This paper characterizes silicon samples using infrared spectroscopy to evaluate their suitability for astronomical applications, focusing on impurity absorption and temperature effects.

Contribution

It provides detailed impurity absorption data and temperature dependence analysis for silicon used in astronomy, with new insights into impurity concentrations.

Findings

Impurity absorption lines identified and characterized.

Temperature dependence of impurity absorption demonstrated.

Doped silicon concentrations determined across a range of resistivities.

Abstract

This work focuses on the characterization of various bulk silicon (Si) samples using Fourier Transform InfraRed (FTIR) and grating spectrometers in order to get them suitable for applications in astronomy. Different samples at different impurity concentrations were characterized by measuring their transmittance in the infrared region. Various lines due to residual impurity absorption were identifed and temperature dependence of impurity absorption is presented. Concentrations of doped samples (rho ~ 0.2 - 25000 Ohm cm) were determined from impurity absorption at low temperatures and from Drude free carrier absorption at 300K.