Abstract

The nonthermal occupation of higher subbands in superlattices by sequential resonant tunneling can give rise to new light emitting devices in the far-infrared spectral region, e.g., by using optical intersubband transitions. In contrast to luminescence spectroscopy,¹ where a homogeneously distributed electron-hole plasma is generated optically, in possible device applications the electrons and holes are injected by ohmic contacts and occupy states according to their vertical transport properties.² Therefore, we have studied the occupation of higher subbands by resonant tunneling in undoped GaAs/AlAs-superlattices (21-nm GaAs, 2.2-nm AlAs, 40 periods) via electroluminescence (EL) spectroscopy at T = 5 K.

© 1994 IEEE