Broadband IR Photoconductivity of a Silicon p-n Junction with the Participation of Donor States of Sulfur and Its Temperature Control

A new physical effect of strong low-temperature broadband (2–40 μm) IR photoconductivity in the p–n junction of silicon formed by an n-hyperdoped layer on a p-doped substrate has been studied. Broadband IR photoconductivity is provided by a clearly pronounced discrete spectrum of neutral and singly ionized donor states of the substitutional atomic impurity and sulfur clusters near the bottom of the conduction band (the so-called “intermediate” band up to 0.6 eV wide), the population distribution within which is smooth over the spectrum, well pronounced, and controlled in amplitude by thermal excitation in the range of 5–250 K. As a result, on the basis of a single silicon photocell, the choice of temperature mode allows registration of radiation in the far-near infrared range for a wide range of diverse practical problems – solar energy, thermal imaging and bioimaging.