Far-Infrared Recombination Radiation from Impact-Ionized Shallow Donors in GaAs

Abstract

Radiation corresponding to transitions from excited shallow donor states and from conduction-band states to the donor ground state has been observed in impact-ionized GaAs at temperatures near 4.2\ifmmode^\circ\else\textdegree\fi{}K. Spectral measurements show a main peak at a wavelength of 282 \ensuremath{\mu} (4.4 meV), corresponding to a $2p\ensuremath{\rightarrow}1s$ transition, and a broader continuum extending to higher photon energies. A total radiated power of ${10}^{\ensuremath{-}7}$ W has been measured corresponding to an external quantum efficiency of about ${10}^{\ensuremath{-}6}$.