1：Experimental Design and Method Selection:

The study involves designing and fabricating SAM-APDs using molecular beam epitaxy, with a focus on electrical characterization, gain and noise analysis, and time response measurements. Theoretical models like the Energy Balance History-Dependent Model (EBHDM) are used for simulation comparisons.

2：Sample Selection and Data Sources:

Devices with mesa diameters of 200 μm and 600 μm were fabricated and tested. Data were collected under dark conditions, with a green laser (λ = 532 nm), and with soft and hard X-rays from synchrotron beamlines (XRD2 and CiPo at Elettra).

3：List of Experimental Equipment and Materials:

Equipment includes a precision frequency LCR meter (HP4284A), a 4-channel picoammeter (AH501 by Elettra), an oscilloscope (KEYSIGHT DSOS404A), and synchrotron radiation sources. Materials involve GaAs/AlGaAs epitaxial layers, chemical etchants (H3PO4:H2O2:H2O solution), metallization layers (Cr, Au, AuGe, Ni), and passivation with SiO

4：Experimental Procedures and Operational Workflow:

Capacitance measurements were performed at reverse biases from 0 V to 35 V using an LCR meter. Current maps were acquired under X-ray illumination at different biases. Gain and noise were measured using laser and X-ray sources, with data analyzed to compute excess noise factor. Time response was measured using the bunch structure of the synchrotron, with signals deconvolved to extract APD response.

5：Data Analysis Methods:

Data analysis included calculating depletion width and dopant concentration from capacitance measurements, gain from photocurrent ratios, excess noise factor from power spectral densities, and time response deconvolution using Fourier transforms and exponentially modified Gaussian fits.