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 (\(\sim \)4 K). Thus, Ge detectors with a-Ge contacts possess the potential to measure a single e–h pair for detecting LDM particles.

中文翻译：

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电荷势垒高度对带有用于轻暗物质搜索的非晶Ge接触的锗（Ge）检测器的影响

在寻找低至MeV规模的暗暗物质（LDM）时，需要能够测量单个电子-空穴（e-h）对的锗（Ge）探测器。我们研究了具有非晶Ge（a-Ge）触点的Ge探测器的可行性，以实现测量单个eh对的灵敏度，这需要极低的泄漏电流。三个具有a-Ge触点的Ge探测器用于研究用于阻挡电子和空穴的电荷势垒高度。使用测得的整体泄漏电流和Döhler-Brodsky模型，我们分别获得了顶部和底部触点的电荷势垒高度和费米能级附近的局部能态密度的值。我们预测，总体泄漏电流非常小，在氦气温度下可以忽略不计（\（\ sim \）4 K）。因此，具有a-Ge接触的Ge探测器具有测量单个e-h对以检测LDM粒子的潜力。