GaAs/Al_0.8Ga_0.2As avalanche photodiodes for soft X-ray spectroscopy

Abstract

The soft X-ray spectroscopic performance of a GaAs/Al 0.8 Ga 0.2 As Separate Absorption and Multiplication (SAM) APD was assessed at room temperature using a 55 Fe source. An energy resolution of 1.08 keV (FWHM) was achieved for the 5.9 keV X-rays, at an avalanche gain of 3.5. The avalanche gain also improved the minimum detectable energy from 4.8 keV at unity gain to about 1.5 keV at a gain of 5. Through avalanche statistics analyses, we confirmed that (i) the APD's FWHM was degraded by X-ray photon absorption within the avalanche region, and (ii) photon absorption in/near the n-cladding layer contributed to an undesirable secondary peak in the spectrum.

An Improved Nonlocal History-Dependent Model for Gain and Noise in Avalanche Photodiodes Based on Energy Balance Equation

“…The model is then applied to template staircase APDs in Sec.IV to demonstrate that it is consistent with the theory in [12]. Comparison with experimental literature data for heterojunction [4], [5] and staircase APDs [2] is provided in Sec.V. Conclusions are finally drawn in Sec.VI.…”

“…In this section we apply the EBHDM model to two realistic structures: the Separate Absorption and Multiplication (SAM) GaAs/Al 0.8 Ga 0.2 As APD described in [4], [5] (Fig.5a) and the staircase SAM-APD presented in [2] (Fig.5b).…”

“…These devices have been experimentally characterized in [2], [4], [5] using X-ray sources. For the sake of a fair comparison with experiments, mixed injection has been taken into account in our model.…”

Al0.52In0.48P avalanche photodiodes for soft X-ray spectroscopy

“…Gomes et al have reported a GaAs/Al 0.8 Ga 0.2 As Separate Absorption and Multiplication region Avalanche Photodiode (SAM-APD) with a resolution of 1.08 keV when exposed to 55 Fe source [5]. The effect of avalanche gain improved the resolution.…”

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

“…A GaAs/AlGaAs SAM‐APD comprised of a 4.5 µm absorption region and a staircase‐like multiplication region has been developed for X‐ray photo‐detection . Meanwhile, a similar GaAs/Al 0.8 Ga 0.2 As SAM‐APD structure has been also demonstrated to detect soft X‐rays at 5.9 keV with a full‐width half‐maximum (FWHM) of 1.08 keV . However, its spectroscopic characterizations show an undesired secondary peak located at energy lower than the 5.9 keV peak.…”