We report on a billion-fold reduction in reverse-bias leakage current density (11.3 A/cm(2) to 8.5 nA/cm(2 )at 20 V) across Schottky contacts made to Al0.50Ga0.50N epilayers grown on sapphire. Interdigitated back-to-back Ni/Au Schottky contacts were made to unintentionally doped Al0.50Ga0.50N epilayers grown by metal organic chemical vapor deposition to realize photodetectors with metal-semiconductor-metal geometry. Testing on a self-con-sistent series of samples grown under different conditions revealed that a two-order reduction in screw dislocation density is primarily responsible for the significant reduction in the lateral leakage (dark) current. This observation is validated by conducive atomic force microscopy experiments. Analytical modelling by temperature-dependent current-voltage measurements confirm a screw dislocation mediated carrier transport mechanism. The anomalously high reverse-bias leakage current (mu A-mA) in the highly defective samples is found to be dominated by thermionic field emission (TFE) at low biases and Poole-Frenkel emission (PFE) from a deep donor level at high biases. With a significant improvement in the crystalline quality, a solar-blind photodetector with an EQE of 47%, photo/dark current ratio of 1.4 x 10(5) and transient characteristics of < 20 ms is demonstrated. This study towards understanding the leakage in Al0.50Ga0.50N is expected to benefit the development of various deep-UV devices and GaN-AlGaN based power transistors.

中文翻译：

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Al 0.50 Ga 0.50 N日盲金属-半导体-金属光电探测器中螺位错介导的暗电流分析

我们报告了对在蓝宝石上生长的 Al0.50Ga0.50N 外延层制作的肖特基触点的反向偏置漏电流密度（11.3 A/cm(2) 至 8.5 nA/cm(2) at 20 V）降低了十亿倍。在通过金属有机化学气相沉积生长的无意掺杂的 Al0.50Ga0.50N 外延层上制作了相互交错的背对背 Ni/Au 肖特基触点，以实现具有金属-半导体-金属几何结构的光电探测器。在不同条件下生长的一系列自洽样品的测试表明，螺位错密度的两级降低是横向泄漏（暗）电流显着降低的主要原因。这一观察结果通过有益的原子力显微镜实验得到验证。通过温度相关的电流-电压测量进行的分析建模证实了螺旋位错介导的载流子传输机制。发现高度缺陷样品中异常高的反向偏置漏电流 (μ A-mA) 主要由低偏置下的热电子场发射 (TFE) 和高偏置下深供体水平的普尔-弗伦克尔发射 (PFE) 支配. 随着晶体质量的显着提高，证明了 EQE 为 47%、光/暗电流比为 1.4 x 10(5) 且瞬态特性 < 20 ms 的日盲光电探测器。这项旨在了解 Al0.50Ga0.50N 泄漏的研究预计将有利于各种深紫外器件和基于 GaN-AlGaN 的功率晶体管的开发。发现高度缺陷样品中异常高的反向偏置漏电流 (μ A-mA) 主要由低偏置下的热电子场发射 (TFE) 和高偏置下深供体水平的普尔-弗伦克尔发射 (PFE) 支配. 随着晶体质量的显着改善，证明了 EQE 为 47%、光/暗电流比为 1.4 x 10(5) 且瞬态特性 < 20 ms 的日盲光电探测器。这项旨在了解 Al0.50Ga0.50N 泄漏的研究预计将有利于各种深紫外器件和基于 GaN-AlGaN 的功率晶体管的开发。发现高度缺陷样品中异常高的反向偏置漏电流 (μ A-mA) 主要由低偏置下的热电子场发射 (TFE) 和高偏置下深供体水平的普尔-弗伦克尔发射 (PFE) 支配. 随着晶体质量的显着提高，证明了 EQE 为 47%、光/暗电流比为 1.4 x 10(5) 且瞬态特性 < 20 ms 的日盲光电探测器。这项旨在了解 Al0.50Ga0.50N 泄漏的研究预计将有利于各种深紫外器件和基于 GaN-AlGaN 的功率晶体管的开发。展示了 EQE 为 47%、光/暗电流比为 1.4 x 10(5) 且瞬态特性 < 20 ms 的日盲光电探测器。这项旨在了解 Al0.50Ga0.50N 泄漏的研究预计将有利于各种深紫外器件和基于 GaN-AlGaN 的功率晶体管的开发。展示了 EQE 为 47%、光/暗电流比为 1.4 x 10(5) 且瞬态特性 < 20 ms 的日盲光电探测器。这项旨在了解 Al0.50Ga0.50N 泄漏的研究预计将有利于各种深紫外器件和基于 GaN-AlGaN 的功率晶体管的开发。