Actually we are. A cooled CCD often has noise levels in the low singleThe last several decades of technology improvement say that you're wrong. We're not at the level of counting individual photons yet, so sensors can get smaller without quality loss.
digit photon counts.
That's sensors being used in astrophotography, at an equivalent ISO rating far higher than the 200 (or even 3200) of today's DSLRs. We'll get there eventually, but we've got quite a way to go.
Noise is very temperature dependent, and the quantum efficiency of the detector sets another limit.
You could of course use hydrogen cooling and let the evaporated hydrogen drive fuel cells in stead of batteries, but...
The only other alternative is cascading diodes, but they�d be too large for sensor matrixes and use high voltages, so we�re still in the sci-fi domain :-)
DagT
