A microcrystalline germanium image sensor array. The array includes a
number of pixel circuits fabricated in or on a substrate. Each pixel
circuit comprises a charge collecting electrode for collecting electrical
charges and a readout means for reading out the charges collected by the
charge collecting electrode. A photodiode layer of charge generating
material located above the pixel circuits convert electromagnetic
radiation into electrical charges. This photodiode layer includes
microcrystalline germanium and defines at least an n-layer, and i-layer
and a p-layer. The sensor array also includes and a surface electrode in
the form of a grid or thin transparent layer located above the layer of
charge generating material. The sensor is especially useful for imaging
in visible and near infrared spectral regions of the electromagnetic
spectrum and provides imaging with starlight illumination.