The impact of the charge barrier height on Germanium (Ge) detectors with amorphous-Ge contacts for light dark matter searches

Abstract

Germanium (Ge) detectors with ability of measuring a single electron-hole (e-h) pair are needed in searching for light dark matter (LDM) down to the MeV scale. We investigate the feasibility of Ge detectors with amorphous-Ge (a-Ge) contacts to achieve the sensitivity of measuring a single e-h pair, which requires extremely low leakage current. Three Ge detectors with a-Ge contacts are used to study the charge barrier height for blocking electrons and holes. Using the measured bulk leakage current and the Döhler-Brodsky model, we obtain the values for charge barrier height and the density of localized energy states near the Fermi energy level for the top and bottom contacts, respectively. We predict that the bulk leakage current is extremely small and can be neglected at helium temperature (∼4 K). Thus, Ge detectors with a-Ge contacts possess the potential to measure a single e-h pair for detecting LDM particles.

Characterization of high-purity germanium detectors with amorphous germanium contacts in cryogenic liquids

“…Leakage currents measured at higher temperatures were higher than those at lower temper- atures. Such a temperature dependence is well documented in the literature [41][42][43][44][45][46][47]. The difference between the LAr and vacuum measurements at similar temperatures may have two possible explanations.…”

“…A detailed study of the leakage currents of the USD detectors can be found in Ref. [47]. On average, the bulk leakage is around a few pA, the surface leakage is around a few tens of pA, at 78 K. In contrast, detectors made at LBNL using USD crystals typically have a combined leakage below 1 pA.…”

Controlling barrier height and spectral responsivity of p–i–n based GeSn photodetectors via arsenic incorporation

“…It is seen that the barrier heights of the prepared junctions range between 0.61 to 0.84 eV and are higher than the barrier height of germanium-based diodes, which have values in the range of 0.2–0.3 eV. 54,55 This gives the prepared samples a good chance to contribute to germanium based photodetection applications.…”

Characterization of High-Purity Germanium Detectors with Amorphous Germanium Contacts in Cryogenic Liquids

“…A detailed study of the leakage currents of the USD detectors can be found in Ref. [37]. On average, the bulk leakage is around a few pA, the surface leakage is around a few tens of pA, at 78 K. In contrast, detectors made at LBNL using USD crystals typically have a combined leakage below 1 pA.…”