ROOM-TEMPERATURE OPERATION OF EPITAXIALLY GROWN SI SI0.5GE0.5/SI RESONANT INTERBAND TUNNELING DIODES/

Resonant interband tunneling diodes on silicon substrates are demonstr ated using a Si/Si0.5Ge0.5/Si heterostructure grown by low temperature molecular beam epitaxy which utilized both a central intrinsic spacer and delta-doped injectors. A low substrate temperature of 370 degrees C was used during growth to ensure a high level of dopant incorporati on. A B delta-doping spike lowered the barrier for holes to populate t he quantum well at the valence band discontinuity, and an Sb delta-dop ing reduces the doping requirement of the n-type bulk Si by producing a deep n(+) well. Samples studied from the as-grown wafers showed no e vidence of negative differential resistance (NDR). The effect of postg rowth rapid thermal annealing temperature was studied on tunnel diode properties. Samples which underwent heat treatment at 700 and 800 degr ees C for 1 min, in contrast, exhibited NDR behavior. The peak-to-vall ey current ratio (PVCR) and peak current density of the tunnel diodes were found to depend strongly on delta-doping placement and on the ann ealing conditions. PVCRs ranging up to 1.54 were measured at a peak cu rrent density of 3.2 kA/cm(2). (C) 1998 American Institute of Physics. [S0003-6951(98)04841-4].