Energy-Sensitive GaSb/AlAsSb Separate Absorption and Multiplication Avalanche Photodiodes for X-Ray and Gamma-Ray Detection

摘要

Demonstrated are antimony-based (Sb-based) separate absorption and multiplication avalanche photodiodes (SAM-APDs) for X-ray and gamma-ray detection, which are composed of GaSb absorbers and large bandgap AlAsSb multiplication regions in order to enhance the probability of stopping high-energy photons while drastically suppressing the minority carrier diffusion. Well-defined X-ray and gamma-ray photopeaks are observed under exposure to Am-241 radioactive sources, demonstrating the desirable energy-sensitive detector performance. Spectroscopic characterizations show a significant improvement of measured energy resolution due to reduced high-peak electric field in the absorbers and suppressed nonradiative recombination on surfaces. Additionally, the GaSb/AlAsSb SAM-APDs clearly exhibit energy response linearity up to 59.5 keV with a minimum full-width half-maximum of 1.283 keV. A further analysis of the spectroscopic measurement suggests that the device performance is intrinsically limited by the noise from the readout electronics rather than that from the photodiodes. This study provides a first understanding of Sb-based energy-sensitive SAM-APDs and paves the way to achieving efficient detection of high-energy photons for X-ray and gamma-ray spectroscopy.