Hot electrons in a nanowire hard X-ray detector

Abstract

Nanowire chip-based electrical and optical devices such as biochemical sensors, physical detectors, or light emitters combine outstanding functionality with a small footprint, reducing expensive material and energy consumption. The core functionality of many nanowire-based devices is embedded in their p-n junctions. To fully unleash their potential, such nanowire-based devices require – besides a high performance – stability and reliability. Here, we report on an axial p-n junction GaAs nanowire X-ray detector that enables ultra-high spatial resolution (~200 nm) compared to micron scale conventional ones. In-operando X-ray analytical techniques based on a focused synchrotron X-ray nanobeam allow probing the internal electrical field and observing hot electron effects at the nanoscale. Finally, we study device stability and find a selective hot electron induced oxidization in the n-doped segment of the p-n junction. Our findings demonstrate capabilities and limitations of p-n junction nanowires, providing insight for further improvement and eventual integration into on-chip devices.

Off-axis multilayer zone plate with 16 nm × 28 nm focus for high-resolution X-ray beam induced current imaging

“…XBIC has been used to investigate the nanoscale carrier dynamics in many types of semiconductors, using established X-ray focusing methods (Zapf et al, 2020;Chayanun et al, 2019b;Stuckelberger et al, 2017). The spatial resolution is limited by the X-ray focus size, reaching around or slightly below 50 nm with established optics, and it is highly desirable to base XBIC on novel high-resolution optics such as MZPs.…”

Analytical and Numerical Investigation of Nanowire Transistor X-ray Detector

“…Semiconductor nanowires (NWs) have demonstrated auspicious performance in multi-diverse fields such as light-emitting diodes [ 1 ], transistors [ 2 , 3 , 4 ], FETs [ 5 ], solar cells [ 6 , 7 , 8 , 9 , 10 , 11 ], lasers [ 12 , 13 ], and quantum physics [ 14 ], as well as their use in light detection in the infrared to the ultraviolet range [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Furthermore, X-ray detection has been exhibited in single NW detectors [ 23 , 24 ] thanks to their long penetration depth. The need for the enhanced spatial resolution of X-ray microscopy is increasing because of the growing attention to nanomaterials [ 25 , 26 ].…”

Nanoscale X-ray detectors based on individual CdS, SnO2 and ZnO nanowires

“…However, there are very few reports on X-ray beam induced current (XBIC) measurements in 1D semiconductor nanostructures. Ronning et al have studied Ga/GaAs heterojunction embedded in a silicon NW with a SiO2 shell in detail using a nanofocused X-ray beam and a combinatory approach [19] as well as demonstrated GaAs NW hard X-ray detection capability [20]. Wallentin et al have extensively employed synchrotron radiation and the XBIC method together with X-ray fluorescence and diffraction measurements in InP and InGaP NWs to study doping [21], mechanical strain [22], charge carrier collection in single-NW solar cells [23], electrical detection of X-ray absorption fine structure [24] and to develop a novel nanoscale measurement technique for a beamline [25].…”