Luminescence from Electron-Hole Drops in Heavily Doped n-Type Germanium

Abstract

Luminescence spectra in As-doped Ge under intense optical excitation have been observed for varying donor concentration 2.0×10¹⁴ to 4.9×10¹⁸ cm⁻³ and for varying average density of electron-hole pairs (e-h pairs) in the crystal. From the variation of the luminescence lineshapes with the average density of e-h pairs and the theoretical analysis of lineshapes, it is found that even in heavily doped Ge the electron-hole drops (EHD) is stably formed in an atmosphere of metallic electrons and ionized donor impurities. Time resolved spectra at extremly high excitation levels confirm the EHD model of non-equilibrium plasma in heavily doped Ge.