  We report quantum coherent oscillations of photocapacitance of a
double-barrier resonant tunneling heterostructure with bias at 10 K. Periodic
presence and absence of sharp excitonic transitions in photocapacitance spectra
with increasing bias demonstrate strong coupling between InAs quantum dots (0D)
and triangular GaAs quantum well (2D). Coherent resonant tunneling in this
0D-2D heterostructure establishes the momentum space narrowing of excitonic
Bose-Einstein Condensation. Drastic increase of indirect exciton densities
below 70 K reveal that excitonic wave functions anchored with each InAs quantum
dots can laterally overlap across wide region around 200 micron to create a
macroscopic quantum state of excitonic Bose-Einstein condensate. This itself
points out the difficulties encountered in the usual 2D-2D bilayers and coupled
quantum well samples used earlier to study excitonic BEC. Finally, we predict
how coupled quantum-dots and quantum-well heterostructures can display
excitonic Bose-Einstein condensation at even higher temperatures.
