Si-based resonant inter- and intraband tunneling diodes

We report on room temperature current voltage characteristics of epitaxiall y grown Si/SiGe/Si p(+)/i/n(+) tunneling diodes based on Si substrate. The structures are prepared by solid source MBE. Very sharp and high p- and n-t ype doping into the 10(20) cm(-3) range is achieved bq boron and phosphorou s using Gap as source material, respectively. Extremely high peak current d ensities (PCD) up to 30 kA cm(-2) and record peal, to valley current ratios (PVCR) of more than 6 are measured at room temperature. These values toget her with intrinsic peak voltages of about V-p = 0.1 V, valley voltages of V -v = 0.4 V and a voltage swing of V-s = 0.8 V fulfill the requirements for typical digital circuit applications. In the second type of interband tunne ling diodes we prepared Si n(+)/p(+)/n(+) structures. First results indicat e a room temperature PVCR up to 2. In the second part we present a new conc ept for resonant p/i/p intraband tunneling diodes based on self-assembled G e islands. The structure consists of closely stacked and vertically aligned Ge islands formed by Stranski Krastanov growth. The aligned Ge islands cre ate vertical channels with energetically deep thermalization layers and hig h Si double barriers for holes in the valence band. Ge islands provide acce ss to larger band offsets as compared to formerly investigated tunneling st ructures with planar pseudomorphic SiGe quantum well layers. First measurem ents of I-V characteristics show two resonances which are attributed to hea vy-heavy hole (hh) and heavy-light hole (Ih) transitions. The lh resonance shows negative differential resistance up to temperatures above 50 K. (C) 2 001 Elsevier Science B.V. All rights reserved.