1.54 mu m Light emitting devices based on Er/O-doped Si layered structuresgrown by molecular beam epitaxy

Two types of Si:Er light emitting devices have been processed and character ized with an aim to efficiently use hot electrons for impact excitation. On e is a p(+)-SiGe/i-Si/n-Si:Er:O/n(+)-Si tunneling diode with a design favor ing electron tunneling from the SiGe valence band to the Si conduction band and subsequent acceleration. Another type of Si:Er light emitters is based on a heterojunction bipolar transistor (HBT) structure containing an Er-do ped active layer in the collector. In these devices, one can introduce hot: electrons from the HBT emitter in a controlled way with a collector bias v oltage prior to the avalanche breakdown to improve the impact excitation ef ficiency. Intense electroluminescence was observed at 300 K at low current (0.1 A cm(-2)) and low bias (3 V). An impact cross-section value of 1 x 10( -14) cm(2) has been estimated, which is a 100-fold increase compared with t he values reported from any other type of Er-doped LEDs. (C) 2001 Elsevier Science B.V. All rights reserved.