Non-uniformly doped graded-gap AlxGa1−xAs X-ray detectors with high photovoltaic response

Graded-gap AlxGa1−xAs/GaAs X-ray detectors with photovoltaic response have been designed and fabricated. A charge collection efficiency of 100% has been achieved in an AlxGa1−xAs layer with a thickness of 15 μm without application of any bias voltage to the layer. Experimentally, the measured sensitivity achieves 0.9 A/W. Amplification of the photocurrent takes place in the thin (15 μm) AlxGa1−xAs layer, and an efficiency of 5×105 V/W is attained at an absorbed power of 10−7 W. ssibilities of using the new detectors for observation of X-ray images are considered.