Integration of front-end electronics with GaAs pixel detectors: experimental and feasibility analysis

This work aims to study the feasibility of the integration, on the same chip, of GaAs pixel detectors and front-end electronics employing GaAs metal semiconductor FETs (MESFETs) or high electron mobility transistors (HEMTs). The interest of fully integrated GaAs systems lies in X and γ-ray spectroscopy and imaging for scientific, industrial, and medical applications. The system design criteria and the prediction of the performance have been derived on the basis of recent experimental results on semi-insulating GaAs pixel detectors. Measurements of the relevant parameters of GaAs FETs suitable for the stringent requirements of a spectroscopy-grade front-end amplifier are analyzed. It is shown that an optimized GaAs integrated system can reach an electronic noise level below 100 electrons rms (<1 keV FWHM) even at room temperature. Some open problems regarding the detector-electronics integration are highlighted and discussed