Patent ID: 7161155

Claim:
An x-ray detector comprising: a. at least one scintillator configured to convert incident x-ray photons into optical photons; and b. at least one p-i-n epitaxial photodiode coupled to the scintillator for detecting optical photons and converting the detected optical photons into electric charge pulses, the epitaxial photodiode including: i) a negatively doped N + type semiconductor substrate, characterized by a relatively low resistivity; ii) an N-type semiconducting layer epitaxially grown on a surface of said N + semiconductor substrate, said N-type epitaxial layer forming an intrinsic region of said p-i-n diode, said N-type epitaxial layer being characterized by a relatively high resistivity; and iii) a positively doped P + type layer for receiving optical photons, said P + layer being disposed adjacent said epitaxial N layer so that a pn junction is formed between said P + type layer and said epitaxial N-layer; and c. a processor configured to integrate the charge pulses from the epitaxial photodiode to compute a pulse spectrum, and to compute from the pulse spectrum a DQE of the x-ray detector; wherein the DQE of the x-ray detector is at least about 0.4.