Abstract: An apparatus for detecting radiation is provided. In embodiments, at least one sensor is disposed on a surface of a wafer-like substrate. At least one sensor medium is fixed relative to the substrate, optically or electrically coupled to the sensor, and separated from the sensor by no more than the substrate thickness. An electronic signal-processing circuit is connected to the sensor and configured to produce an output when the sensor is stimulated by a product of an interaction between the sensor medium and impinging radiation. The sensor is configured to collect, from the sensor medium, charge and/or light produced within the sensor medium by interactions with impinging radiation.