InAs avalanche photodiodes as X-ray detectors

Abstract

We designed and demonstrated an InAs avalanche photodiode (APD) for X-ray detection, combining narrow band gap semiconductor materials and avalanche gain from APDs. The InAs APD (cooled by liquid nitrogen) was tested with a 55 Fe X-ray source. Full width at half maximum (FWHM) from the spectra decreases rapidly with reverse bias, rising again for higher voltages, resulting in a minimum FWHM value of 401eV at 5.9 keV. This minimum value was achieved at 10 V reverse bias, which corresponds to an avalanche gain of 11. The dependence of FWHM on reverse bias observed is explained by the competition between various factors, such as leakage current, capacitance and avalanche gain from the APD, as well as measurement system noise. The minimum FWHM achieved is largely dominated by the measurement system noise and APD leakage current.

Characterization of GaSb photodiode for gamma-ray detection

“…A few studies of smallbandgap materials, such as InAs (Z In = 49, Z As = 33) and InSb (Z In = 49, Z Sb = 51), have shown the successful detection of α-particles or soft X-rays at temperatures lower than 80 K, but hard X-ray or gamma-ray energies larger than 10 keV have not yet been detected to the best of our knowledge. [11][12][13][14] GaSb, as one of the popular III-V materials for optoelectronics, [15][16][17][18][19] exhibits a great potential to offer a high spectroscopic performance for a gamma-ray detector. Although lowtemperature operation would be required to minimize leakage noise induced by the small bandgap of GaSb (E g = 0.72 eV at 300 K), the relatively high Z (Z Ga = 31, Z Sb = 51) and low PCE of GaSb predicted using an empirical formula are favorable for high energy resolutions from soft X-ray to gamma-ray energies up to a few hundred keV.…”

Characterization of B‐Site Niobium‐Doped Pr0.4Sr0.6 (Co0.3Fe0.6)1‐xNbxO3‐δ (x=0, 0.05, 0.1, 0.2) Perovskites as Cathode Materials for Solid Oxide Fuel Cells

“…It is a compound containing various metal ions with convertible oxidation states, which could tolerate appreciable vacancies in the anionic sublattices. [8] For a single cubic structure, A site cation is always 12-coordinated with oxygen ions while B site cation is 6-coordinated with oxygen ions. Also, the materials properties could change with the cation ordering.…”