High spatial resolution graded-gap AlxGa1−xAs X-ray detector

Spatial resolution of two types of graded-gap AlxGa1−xAs X-ray detectors, p+-AlxGa1−xAs layer (A type) and p-AlxGa1−xAs −p+-GaAs–p-AlxGa1−xAs structure (B-type), is investigated. Two processes, the diffusion of generated charge and broadening of light beam, cause blurring of X-ray image in the detectors. Optical broadening of light beam was eliminated in B-type structure. The value of spatial resolution mainly depends on the thickness of graded-gap AlxGa1−xAs layer. Spatial resolution of 10 LP/mm for the A-type structure of 50 μm thickness and 25 LP/mm for B-type structure of 18 μm thickness was experimentally observed.