Characterization of 4 inch GaAs:Cr wafers

Abstract

Producing of large area matrix detectors based on semiconductor materials with high atomic number suitable for the registration of the synchrotron radiation of high intensity in the photon energy range 20-90 keV is a relevant technological challenge of our time. This will develop a fundamentally new experimental base of scientific research conducted at leading X-ray synchrotron centers with high luminosity beams. The paper analyzes the possibility of using 4 inch gallium arsenide wafers to create a high-resistive GaAs:Cr detector quality structures on their basis and detector arrays of large area.

Characterization of chromium compensated GaAs as an X-ray sensor material for charge-integrating pixel array detectors

“…The nominal average resistivity of the wafer used in this study was 0.5 GΩcm. Measurements were done using a contactless measurement technique [21,22] at room temperature.…”

“…TSU is currently developing a process to replace the Au layer with a less absorbent Al layer for future sensor fabrications.The nominal average resistivity of the wafer used in this study was 0.5 GΩcm. Measurements were done using a contactless measurement technique [21,22] at room temperature.Since the sensors are fabricated as photoresistors, the dark current is comparatively high and depends strongly on bias and temperature [23]. While this is not much of a problem for most photon counting detectors like the Medipix3 [18], it is an important parameter for integrating detectors, like the one used in this study.The mobility of electrons and holes and their lifetimes was measured at TSU to be 2500 cm 2 /Vs and 40 ns for electrons and 165 cm 2 /Vs and 1.1 ns for holes [22,23].Given the sensor thickness of 500 µm and a bias voltage of 200 V, we expect more than 88 % of electrons to reach the readout electrode before being trapped2, however the probability of holes reaching the electrode before being trapped is practically zero.…”

Influence of temperature on the energy resolution of sensors based on HR GaAs:Cr

“…GaAs n-type wafers grown via a Liquid Encapsulated Czochralski (LEC) method were compensated with chromium using a high temperature annealing process [9]. This compensated material has a high resistivity value of 10 9 Ω×cm and a relatively long electron lifetime [5,6].…”