Hayfaa Alradhi - Academia.edu (original) (raw)

Papers by Hayfaa Alradhi

Nano letters, Mar 8, 2017

Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial in... more Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial insight into the mechanism of carrier recombination and bandedge structure in semiconductors. In this study, mid-infrared PL measurements on vertically aligned InAs nanowires (NWs) are realized for the first time in a wide temperature range of up to 290 K, by which the radiative recombinations are clarified in the NWs grown on n- and p-type Si substrates, respectively. A dominant PL feature is identified to be from the type-II optical transition across the interfaces between the zinc-blend (ZB) and the wurtzite (WZ) InAs, a lower-energy feature at low temperatures is ascribed to impurity-related transition, and a higher-energy feature at high temperatures originates in the interband transition of the WZ InAs being activated by thermal-induced electron transfer. The optical properties of the ZB-on-WZ and WZ-on-ZB interfaces are asymmetric, and stronger nonradiative recombination and weaker ...

Nanotechnology, Jan 10, 2017

InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silic... more InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silicon-based optoelectronics such as infrared photondetectors/emitters and highly sensitive phototransistors, as well as in the generation of renewable electricity. However, producing optically efficient InAsSb NWs with a high Sb content remains a challenge, and optical emission is limited to 4.0 μm due to the quality of the nanowires. Here, we report, for the first time, the success of high-quality and optically efficient InAsSb NWs enabling silicon-based optoelectronics operating in entirely mid-wavelength infrared. Pure zinc-blende InAsSb NWs were realized with efficient photoluminescence emission. We obtained room-temperature photoluminescence emission in InAs NWs and successfully extended the emission wavelength in InAsSb NWs to 5.1 μm. The realization of this optically efficient InAsSb NW material paves the way to realizing next-generation devices, combining advances in III-V semicondu...

Advanced Functional Materials, 2017

The control of optical and transport properties of semiconductor heterostructures is crucial for ... more The control of optical and transport properties of semiconductor heterostructures is crucial for engineering new nanoscale photonic and electrical devices with diverse functions. Core–shell nanowires are evident examples of how tailoring the structure, i.e., the shell layer, plays a key role in the device performance. However, III–V semiconductors bandgap tuning has not yet been fully explored in nanowires. Here, a novel InAs/AlSb core–shell nanowire heterostructure is reported grown by molecular beam epitaxy and its application for room temperature infrared photodetection. The core–shell nanowires are dislocation-free with small chemical intermixing at the interfaces. They also exhibit remarkable radiative emission efficiency, which is attributed to efficient surface passivation and quantum confinement induced by the shell. A high-performance core–shell nanowire phototransistor is also demonstrated with negative photoresponse. In comparison with simple InAs nanowire phototransistor, the core–shell nanowire phototransistor has a dark current two orders of magnitude smaller and a sixfold improvement in photocurrent signal-to-noise ratio. The main factors for the improved photodetector performance are the surface passivation, the oxide in the AlSb shell and the type-II bandgap alignment. The study demonstrates the potential of type-II core–shell nanowires for the next generation of photodetectors on silicon.

Due to increasing demand of nanowires (NWs) in the areas of electrical and photonic devices appli... more Due to increasing demand of nanowires (NWs) in the areas of electrical and photonic devices applications, it is imperative to try to improve their properties that are found to degrade their device performances. This thesis provides an extensive investigation of InAs based NWs for use in the photodetection applications. To achieve this goal, the structural and optical properties of InAs NWs and InAs NW-based quantum materials (e.g., InAsSb NWs, InAs/AlSb NWs and InAs/GaSb core-shell NWs) have been investigated. The NW samples were grown by molecular beam epitaxy (MBE); self-catalysed droplet epitaxy was used as the growth mechanism for them. To improve the optical properties of InAs NWs, we further optimised the MBE growth for the NWs based on our previous growth understanding, which resulted in InAs NWs give strong room temperature photoluminescence (PL) at room temperature. We also notified that the substrate doping type gives significant effect on PL emission. In order to improve ...

Nano letters, Mar 8, 2017

Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial in... more Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial insight into the mechanism of carrier recombination and bandedge structure in semiconductors. In this study, mid-infrared PL measurements on vertically aligned InAs nanowires (NWs) are realized for the first time in a wide temperature range of up to 290 K, by which the radiative recombinations are clarified in the NWs grown on n- and p-type Si substrates, respectively. A dominant PL feature is identified to be from the type-II optical transition across the interfaces between the zinc-blend (ZB) and the wurtzite (WZ) InAs, a lower-energy feature at low temperatures is ascribed to impurity-related transition, and a higher-energy feature at high temperatures originates in the interband transition of the WZ InAs being activated by thermal-induced electron transfer. The optical properties of the ZB-on-WZ and WZ-on-ZB interfaces are asymmetric, and stronger nonradiative recombination and weaker ...

Nanotechnology, Jan 10, 2017

InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silic... more InAsSb nanowires (NWs) with a high Sb content have potential in the fabrication of advanced silicon-based optoelectronics such as infrared photondetectors/emitters and highly sensitive phototransistors, as well as in the generation of renewable electricity. However, producing optically efficient InAsSb NWs with a high Sb content remains a challenge, and optical emission is limited to 4.0 μm due to the quality of the nanowires. Here, we report, for the first time, the success of high-quality and optically efficient InAsSb NWs enabling silicon-based optoelectronics operating in entirely mid-wavelength infrared. Pure zinc-blende InAsSb NWs were realized with efficient photoluminescence emission. We obtained room-temperature photoluminescence emission in InAs NWs and successfully extended the emission wavelength in InAsSb NWs to 5.1 μm. The realization of this optically efficient InAsSb NW material paves the way to realizing next-generation devices, combining advances in III-V semicondu...

Advanced Functional Materials, 2017

The control of optical and transport properties of semiconductor heterostructures is crucial for ... more The control of optical and transport properties of semiconductor heterostructures is crucial for engineering new nanoscale photonic and electrical devices with diverse functions. Core–shell nanowires are evident examples of how tailoring the structure, i.e., the shell layer, plays a key role in the device performance. However, III–V semiconductors bandgap tuning has not yet been fully explored in nanowires. Here, a novel InAs/AlSb core–shell nanowire heterostructure is reported grown by molecular beam epitaxy and its application for room temperature infrared photodetection. The core–shell nanowires are dislocation-free with small chemical intermixing at the interfaces. They also exhibit remarkable radiative emission efficiency, which is attributed to efficient surface passivation and quantum confinement induced by the shell. A high-performance core–shell nanowire phototransistor is also demonstrated with negative photoresponse. In comparison with simple InAs nanowire phototransistor, the core–shell nanowire phototransistor has a dark current two orders of magnitude smaller and a sixfold improvement in photocurrent signal-to-noise ratio. The main factors for the improved photodetector performance are the surface passivation, the oxide in the AlSb shell and the type-II bandgap alignment. The study demonstrates the potential of type-II core–shell nanowires for the next generation of photodetectors on silicon.

Due to increasing demand of nanowires (NWs) in the areas of electrical and photonic devices appli... more Due to increasing demand of nanowires (NWs) in the areas of electrical and photonic devices applications, it is imperative to try to improve their properties that are found to degrade their device performances. This thesis provides an extensive investigation of InAs based NWs for use in the photodetection applications. To achieve this goal, the structural and optical properties of InAs NWs and InAs NW-based quantum materials (e.g., InAsSb NWs, InAs/AlSb NWs and InAs/GaSb core-shell NWs) have been investigated. The NW samples were grown by molecular beam epitaxy (MBE); self-catalysed droplet epitaxy was used as the growth mechanism for them. To improve the optical properties of InAs NWs, we further optimised the MBE growth for the NWs based on our previous growth understanding, which resulted in InAs NWs give strong room temperature photoluminescence (PL) at room temperature. We also notified that the substrate doping type gives significant effect on PL emission. In order to improve ...