Synchrotron experiment will help to improve gallium arsenide sensors

29 October 2019

Radiophysicist Anastasia Lozinskaya has conducted an experiment on the Diamond Light Source synchrotron in the Rutherford Appleton Laboratory (RAL) in the UK. She irradiated a sensor based on gallium arsenide compensated by chromium (HR GaAs: Cr), created at TSU with a beam of synchrotron radiation. The data obtained will help to improve the quality of the sensors and make the final picture more uniform.

- Recently some defects were detected in the structure of gallium arsenide, which we compensate for chromium. These defects lead to a change in the counting speed of the sensors, and as a result, the picture becomes heterogeneous, that is, small “spots” are visible with more or less charge collected, - said Anastasia Lozinskaya, junior scientific researcher at the center for research and development Advanced Technologies in Microelectronics. - In early 2019, we applied to Diamond Light Source for an experiment to improve the quality of our sensors.

The experiment was held in the Rutherford Appleton Laboratory, where the Diamond synchrotron operates. This is currently the largest scientific facility in the UK.

- We shot a small beam of synchrotron radiation (0.01 x 0.01 mm) at the sensor - into the area where, as we believed, there are defects. In theory, such a beam size should give us a good resolution, and we can see everything, - Anastasia Lozinskaya explained.

The 2.4 x 2.4 cm detector is an array of 6,400 pixels. During the experiment, the radiophysicist performed about 6,400 exposures. The researcher checked the 4x4 pixel area with a beam with different energy, giving a different depth of absorption of the beam.

- In 4 days we collected 8 terabytes of data, which are now being processed by our colleagues from the Rutherford Appleton Laboratory. The first results will be ready in a few months, said Anastasia Lozinskaya. - We changed the depth of radiation absorption, so the results obtained will help us determine the nature of the defects and eliminate them in the future.

Gallium arsenide detectors are a unique development of a team of Tomsk scientists under the guidance of TSU Professor Oleg Tolbanov. These detectors have no world analogs. They are used at the DESY German synchrotron center, at the Large Hadron Collider at CERN, and other leading research centers.