Session: Research Posters

Paper Number: 114406

114406 - Photovoltaic Effect on Metal/insulator/semiconductor (Mis) Based Magnetic Tunnel Junction-Based Molecular Spintronics Devices 

When light of a suitable wavelength strikes a solar cell system, an electric current or voltage is generated. This process is known as the photovoltaic effect (PV). The energy harnessed in this process by the solar cell is converted into electrical signals which have the capacity to boost the discovery of new photo voltaic systems realized from common materials like Nickel Iron (NiFe), Aluminum Oxide (AlOx), and Silicon (Si). This paper investigates the observation of the Photovoltaic (PV) effect on a Magnetic Tunnel Junction Molecular Spintronics Device (MTJMSD). The Magnetic Tunnel Junction (MTJ) in this case is composed of Metal/Insulator/Semiconductor (MIS); NiFe/AlOx/Si, respectively, and a Molecule across the cross-junction of the exposed side edges of the MTJ. The SMM creates a molecular channel between the two electrodes through which electrons can spin from one ferromagnet to the other. After the molecular bridge was established, we observed a substantial increase in exchange coupling and photovoltaic effect.

This paper pivots on the photovoltaic (PV) effect. Compared to the controlled experiment that resulted in no noticeable change, we observed the photovoltaic effect on the ferromagnetic electrode in the MTJ after the Molecule was attached. The experiment was conducted in (i) darkness and under (ii) light, representing the ground state and the excited states of the electrons respectively, and (iii) using a solar simulator for lights of different intensities. A sizeable increase in the photovoltaic effect was observed under lighting conditions than in darkness. The increase was more dramatic with an increase in light intensity under the solar simulator. Light is composed of photons, which are simply small bundles of electromagnetic radiation or energy. These photons can be absorbed by a photovoltaic cell.  This suggests that under light, photons are given up exciting electrons from the valence band to higher energy states conduction band within the material. Particularly, this occurs when the energy of the photons from the light is larger than the band gap of the semiconductor.  The energy is specifically transferred to the electrons in the electrode in this case the semiconductor, causing the electrons to jump to a higher energy state known as the conduction band. This leaves behind a "hole" in the valence band that the electron jumped up from. This movement of the electron as a result of added energy creates two charge carriers, an electron-hole pair. This paper lays the groundwork for further investigation of the similar photovoltaic effect on other combinations of MTJs and promising magnetic molecules. This study presents the blueprint that can lead to the mass production of low-cost spin photovoltaic devices.

Presenting Author: Pius Suh University of The District of Columbia

Presenting Author Biography: Pius Suh is a graduate student in the NSF-CREST Center for Nanotechnology Research and Education at the University of the District of Columbia. He is researching in the field of Molecular Spintronics Device-based chemical sensors. Pius is engaged in experimental research and has been developing a number of instruments for magnetic and transport studies. He is conducting the Monte Carlo Simulation based Molecular Spintronics Device Research. He is currently working on a project to study the impact of magnetic anisotropy on molecular devices.

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