Technology and Performance Study of a Two-Line Monolithic X- and $\gamma$-Ray Detection Chip Based on Semi-Insulating GaAs

Technology, electrical characteristics and detection performance of a novel recently developed and fabricated 64-pixel two-line array chip for detection of X- and
$\gamma$
-rays based on semi-insulating GaAs from three different producers are reported and compared. The chip has dimensions of cca (16
$\,\times\,$
4
$\,\times\,$
0.25) mm
$^{3}$
. A single pixel has an active area of (300
$\,\times\,$
190)
$\mu$
m
$^{2}$
with a pitch of 250
$\mu$
m. The distance between two lines is 360
$\mu$
m. The reverse current density (at 295 K) of a single pixel at a bias voltage of 200 V ranges from 90 to 140 nA/mm
$^{2}$
. The breakdown voltage ranges between 250 and 500 V. Pulse-height spectra of radionuclide
$^{241}\!$
Am in the top irradiation mode are demonstrated. The best spectrometric performance is achieved with the Freiberger material. The charge collection efficiency of about 85% and energy resolution in the full width at half maximum better than 8.6 keV for the 59.5 keV photopeak was reached at 295 K and bias of 300 V.